任务 · 字符串 困难 JavaScript ·

Brace expansion

/**
 * @param {string} s
 * @returns {string[]}
 */
function brace_expand(s)

brace_expand("a{b,c}d")  // -> ["abd", "acd"]
brace_expand("{a,b}{c,d}")  // -> ["ac", "ad", "bc", "bd"]
brace_expand("{a}")  // -> ["{a}"]

• 第 1 名Google Gemini 3.8 Flash未解决 · 通过 21/22 个测试生成耗时 9.6 秒 · 执行耗时 743 毫秒 · $0.0053

  ✓	brace_expand("a{b,c}d")预期 ["abd", "acd"]	21 毫秒
  ✓	brace_expand("{a,b}{c,d}")预期 ["ac", "ad", "bc", "bd"]	<1 毫秒
  ✓	brace_expand("{a}")预期 ["{a}"]	2 毫秒

  ✓ <1 毫秒✓ 2 毫秒✓ 1 毫秒✓ 1 毫秒✓ 2 毫秒✓ 2 毫秒✓ 2 毫秒✓ 3 毫秒✓ <1 毫秒✓ <1 毫秒✓ <1 毫秒✓ 2 毫秒✓ <1 毫秒✓ <1 毫秒✓ 1 毫秒✓ 1 毫秒⏱ 超出时间限制⏱ 63 毫秒⏱ 335 毫秒
  代码

  /**
   * @param {string} s
   * @returns {string[]}
   */
  function brace_expand(s) {
    const n = s.length;
    // Step 1: Match braces
    // Braces are matched left to right: each '}' closes nearest unclosed '{'.
    // Unmatched braces are ordinary characters.
    const match = new Int32Array(n).fill(-1);
    const stack = [];
    for (let i = 0; i < n; i++) {
      if (s.charCodeAt(i) === 123) { // '{'
        stack.push(i);
      } else if (s.charCodeAt(i) === 125) { // '}'
        if (stack.length > 0) {
          const open = stack.pop();
          match[open] = i;
          match[i] = open;
        }
      }
    }
  
    // Step 2: Determine for each matched '{' whether it is a valid group (has comma directly inside)
    const isGroup = new Uint8Array(n);
    for (let i = 0; i < n; i++) {
      if (s.charCodeAt(i) === 123 && match[i] !== -1) {
        const close = match[i];
        let hasComma = false;
        let j = i + 1;
        while (j < close) {
          const c = s.charCodeAt(j);
          if (c === 44) { // ','
            hasComma = true;
            break;
          }
          if (c === 123 && match[j] !== -1) {
            j = match[j] + 1;
          } else {
            j++;
          }
        }
        if (hasComma) {
          isGroup[i] = 1;
        }
      }
    }
  
    // Parse [start, end) into an AST or expand directly
    // Note: result has at most 100,000 strings.
    // Recursion depth up to 300 levels deep.
    function expand(start, end) {
      // Collect sequence of parts
      const parts = [];
      let i = start;
      let literalBuf = '';
  
      while (i < end) {
        const c = s.charCodeAt(i);
        if (c === 123 && match[i] !== -1 && match[i] < end) {
          const close = match[i];
          if (isGroup[i]) {
            if (literalBuf.length > 0) {
              parts.push([literalBuf]);
              literalBuf = '';
            }
            // Split by top-level commas inside [i + 1, close)
            const alternatives = [];
            let segStart = i + 1;
            let k = i + 1;
            while (k < close) {
              const kc = s.charCodeAt(k);
              if (kc === 44) { // ','
                alternatives.push(expand(segStart, k));
                segStart = k + 1;
                k++;
              } else if (kc === 123 && match[k] !== -1 && match[k] < close) {
                k = match[k] + 1;
              } else {
                k++;
              }
            }
            alternatives.push(expand(segStart, close));
            
            // Flatten alternatives
            const groupRes = [];
            for (const alt of alternatives) {
              for (let a = 0; a < alt.length; a++) {
                groupRes.push(alt[a]);
              }
            }
            parts.push(groupRes);
            i = close + 1;
          } else {
            // Matched pair without top-level comma: kept literally, braces included,
            // though groups inside it still expand!
            // "{a}" -> literal '{', expand(a), literal '}'
            if (literalBuf.length > 0) {
              parts.push([literalBuf]);
              literalBuf = '';
            }
            const inner = expand(i + 1, close);
            const preserved = new Array(inner.length);
            for (let idx = 0; idx < inner.length; idx++) {
              preserved[idx] = '{' + inner[idx] + '}';
            }
            parts.push(preserved);
            i = close + 1;
          }
        } else {
          literalBuf += s[i];
          i++;
        }
      }
  
      if (literalBuf.length > 0) {
        parts.push([literalBuf]);
      }
  
      if (parts.length === 0) {
        return [''];
      }
  
      // Cartesian product of parts
      let current = parts[0];
      for (let p = 1; p < parts.length; p++) {
        const nextPart = parts[p];
        const nextLen = nextPart.length;
        const curLen = current.length;
        const combined = new Array(curLen * nextLen);
        let ptr = 0;
        for (let cIdx = 0; cIdx < curLen; cIdx++) {
          const prefix = current[cIdx];
          for (let nIdx = 0; nIdx < nextLen; nIdx++) {
            combined[ptr++] = prefix + nextPart[nIdx];
          }
        }
        current = combined;
      }
  
      return current;
    }
  
    return expand(0, n);
  }

  二次尝试

  未解决 · 通过 21/22 个测试生成耗时 13 秒 · $0.0074

  模型可以看到失败的测试数量、包含预期值和返回值的失败示例，以及隐藏测试未通过的原因（不含输入数据）。此成绩不计入排名或评分。

  ✓	brace_expand("a{b,c}d")预期 ["abd", "acd"]	3 毫秒
  ✓	brace_expand("{a,b}{c,d}")预期 ["ac", "ad", "bc", "bd"]	2 毫秒
  ✓	brace_expand("{a}")预期 ["{a}"]	1 毫秒

  ✓ <1 毫秒✓ 1 毫秒✓ 3 毫秒✓ 2 毫秒✓ 2 毫秒✓ 2 毫秒✓ 2 毫秒✓ 1 毫秒✓ 1 毫秒✓ <1 毫秒✓ 2 毫秒✓ 2 毫秒✓ 1 毫秒✓ 2 毫秒✓ 1 毫秒✓ <1 毫秒⏱ 超出时间限制⏱ 43 毫秒⏱ 187 毫秒

  代码

  /**
   * @param {string} s
   * @returns {string[]}
   */
  function brace_expand(s) {
    const n = s.length;
    if (n === 0) return [''];
  
    const match = new Int32Array(n).fill(-1);
    const stack = [];
    for (let i = 0; i < n; i++) {
      const code = s.charCodeAt(i);
      if (code === 123) { // '{'
        stack.push(i);
      } else if (code === 125) { // '}'
        if (stack.length > 0) {
          const open = stack.pop();
          match[open] = i;
          match[i] = open;
        }
      }
    }
  
    // Check if each matched brace contains any unnested comma or groups inside
    // hasGroup[i] = whether anything expands inside (groups or nested groups)
    const isGroup = new Uint8Array(n);
    const hasExpansion = new Uint8Array(n);
  
    for (let i = n - 1; i >= 0; i--) {
      if (s.charCodeAt(i) === 123 && match[i] !== -1) {
        const close = match[i];
        let hasComma = false;
        let anyExpand = false;
        let j = i + 1;
        while (j < close) {
          const c = s.charCodeAt(j);
          if (c === 44) {
            hasComma = true;
            j++;
          } else if (c === 123 && match[j] !== -1 && match[j] < close) {
            if (isGroup[j] || hasExpansion[j]) {
              anyExpand = true;
            }
            j = match[j] + 1;
          } else {
            j++;
          }
        }
        if (hasComma) {
          isGroup[i] = 1;
          hasExpansion[i] = 1;
        } else if (anyExpand) {
          hasExpansion[i] = 1;
        }
      }
    }
  
    // Quick check: does the whole string have any group expansion?
    let hasAnyGroup = false;
    for (let i = 0; i < n; i++) {
      if (isGroup[i]) {
        hasAnyGroup = true;
        break;
      }
    }
    if (!hasAnyGroup) {
      return [s];
    }
  
    function expand(start, end) {
      const parts = [];
      let i = start;
      let litStart = start;
  
      while (i < end) {
        const c = s.charCodeAt(i);
        if (c === 123 && match[i] !== -1 && match[i] < end) {
          const close = match[i];
          if (isGroup[i]) {
            if (i > litStart) {
              parts.push([s.slice(litStart, i)]);
            }
  
            const groupRes = [];
            let segStart = i + 1;
            let k = i + 1;
            while (k < close) {
              const kc = s.charCodeAt(k);
              if (kc === 44) {
                const alt = expand(segStart, k);
                for (let a = 0; a < alt.length; a++) groupRes.push(alt[a]);
                segStart = k + 1;
                k++;
              } else if (kc === 123 && match[k] !== -1 && match[k] < close) {
                k = match[k] + 1;
              } else {
                k++;
              }
            }
            const lastAlt = expand(segStart, close);
            for (let a = 0; a < lastAlt.length; a++) groupRes.push(lastAlt[a]);
  
            parts.push(groupRes);
            i = close + 1;
            litStart = i;
          } else if (hasExpansion[i]) {
            if (i > litStart) {
              parts.push([s.slice(litStart, i)]);
            }
            const inner = expand(i + 1, close);
            const preserved = new Array(inner.length);
            for (let idx = 0; idx < inner.length; idx++) {
              preserved[idx] = '{' + inner[idx] + '}';
            }
            parts.push(preserved);
            i = close + 1;
            litStart = i;
          } else {
            // No expansion inside this brace pair, treat entire { ... } as literal
            i = close + 1;
          }
        } else {
          i++;
        }
      }
  
      if (i > litStart) {
        parts.push([s.slice(litStart, i)]);
      }
  
      if (parts.length === 0) {
        return [''];
      }
  
      let current = parts[0];
      for (let p = 1; p < parts.length; p++) {
        const nextPart = parts[p];
        const nextLen = nextPart.length;
        const curLen = current.length;
  
        if (curLen === 1 && current[0] === '') {
          current = nextPart;
          continue;
        }
        if (nextLen === 1 && nextPart[0] === '') {
          continue;
        }
  
        if (nextLen === 1) {
          const suffix = nextPart[0];
          const combined = new Array(curLen);
          for (let cIdx = 0; cIdx < curLen; cIdx++) {
            combined[cIdx] = current[cIdx] + suffix;
          }
          current = combined;
        } else if (curLen === 1) {
          const prefix = current[0];
          const combined = new Array(nextLen);
          for (let nIdx = 0; nIdx < nextLen; nIdx++) {
            combined[nIdx] = prefix + nextPart[nIdx];
          }
          current = combined;
        } else {
          const combined = new Array(curLen * nextLen);
          let ptr = 0;
          for (let cIdx = 0; cIdx < curLen; cIdx++) {
            const prefix = current[cIdx];
            for (let nIdx = 0; nIdx < nextLen; nIdx++) {
              combined[ptr++] = prefix + nextPart[nIdx];
            }
          }
          current = combined;
        }
      }
  
      return current;
    }
  
    return expand(0, n);
  }

• 第 2 名OpenAI GPT-6.1 Terra未解决 · 通过 20/22 个测试生成耗时 10 秒 · 执行耗时 781 毫秒 · $0.0046

  ✓	brace_expand("a{b,c}d")预期 ["abd", "acd"]	3 毫秒
  ✓	brace_expand("{a,b}{c,d}")预期 ["ac", "ad", "bc", "bd"]	1 毫秒
  ✓	brace_expand("{a}")预期 ["{a}"]	2 毫秒

  ✓ <1 毫秒✓ 1 毫秒✓ 1 毫秒✓ 1 毫秒✓ 6 毫秒✓ 2 毫秒✓ 2 毫秒✓ 28 毫秒✓ <1 毫秒✓ 2 毫秒✓ <1 毫秒✓ <1 毫秒✓ 3 毫秒✓ 2 毫秒✓ 1 毫秒✓ 1 毫秒⏱ 超出时间限制⏱ 53 毫秒⏱ 超出时间限制
  代码

  function brace_expand(s) {
    const n = s.length;
    const match = new Int32Array(n);
    match.fill(-1);
  
    const stack = [];
    for (let i = 0; i < n; i++) {
      const c = s.charCodeAt(i);
      if (c === 123) {
        stack.push(i);
      } else if (c === 125 && stack.length) {
        const open = stack.pop();
        match[open] = i;
      }
    }
  
    // Parse matched pairs into concatenation and alternative nodes.
    // Unmatched braces are included in literal substrings.
    const root = { parts: [], start: 0, open: -1, alternatives: null };
    const frames = [root];
  
    for (let i = 0; i < n; i++) {
      const frame = frames[frames.length - 1];
      const c = s.charCodeAt(i);
  
      if (c === 123 && match[i] !== -1) {
        if (frame.start < i) frame.parts.push(s.slice(frame.start, i));
        frames.push({ parts: [], start: i + 1, open: i, alternatives: null });
      } else if (c === 44 && frame.open !== -1) {
        if (frame.start < i) frame.parts.push(s.slice(frame.start, i));
        if (frame.alternatives === null) frame.alternatives = [];
        frame.alternatives.push(frame.parts);
        frame.parts = [];
        frame.start = i + 1;
      } else if (c === 125 && frame.open !== -1 && match[frame.open] === i) {
        if (frame.start < i) frame.parts.push(s.slice(frame.start, i));
        frames.pop();
  
        let node;
        if (frame.alternatives !== null) {
          frame.alternatives.push(frame.parts);
          node = { alternatives: frame.alternatives };
        } else {
          node = { literalBraces: true, parts: frame.parts };
        }
  
        const parent = frames[frames.length - 1];
        parent.parts.push(node);
        parent.start = i + 1;
      }
    }
    if (root.start < n) root.parts.push(s.slice(root.start));
  
    function combine(left, right) {
      if (right.length === 1 && right[0] === "") return left;
      if (left.length === 1 && left[0] === "") return right;
      const result = new Array(left.length * right.length);
      let k = 0;
      for (let i = 0; i < left.length; i++) {
        for (let j = 0; j < right.length; j++) {
          result[k++] = left[i] + right[j];
        }
      }
      return result;
    }
  
    function expandParts(parts) {
      let result = [""];
      for (let i = 0; i < parts.length; i++) {
        const part = parts[i];
        let values;
        if (typeof part === "string") {
          values = [part];
        } else if (part.literalBraces) {
          values = expandParts(part.parts);
          for (let j = 0; j < values.length; j++) {
            values[j] = "{" + values[j] + "}";
          }
        } else {
          values = [];
          for (let j = 0; j < part.alternatives.length; j++) {
            const expanded = expandParts(part.alternatives[j]);
            for (let k = 0; k < expanded.length; k++) values.push(expanded[k]);
          }
        }
        result = combine(result, values);
      }
      return result;
    }
  
    return expandParts(root.parts);
  }

  二次尝试

  未解决 · 通过 20/22 个测试生成耗时 11 秒 · $0.0064

  模型可以看到失败的测试数量、包含预期值和返回值的失败示例，以及隐藏测试未通过的原因（不含输入数据）。此成绩不计入排名或评分。

  ✓	brace_expand("a{b,c}d")预期 ["abd", "acd"]	4 毫秒
  ✓	brace_expand("{a,b}{c,d}")预期 ["ac", "ad", "bc", "bd"]	3 毫秒
  ✓	brace_expand("{a}")预期 ["{a}"]	2 毫秒

  ✓ 4 毫秒✓ 2 毫秒✗ 答案错误✓ 2 毫秒✓ 3 毫秒✓ 1 毫秒✓ 2 毫秒✓ 2 毫秒✓ 1 毫秒✓ <1 毫秒✓ 1 毫秒✓ 1 毫秒✓ 2 毫秒✓ 1 毫秒✓ 1 毫秒✓ 1 毫秒⏱ 超出时间限制⏱ 68 毫秒⏱ 208 毫秒

  代码

  function brace_expand(s) {
    const n = s.length;
    const match = new Int32Array(n);
    match.fill(-1);
    const stack = [];
  
    for (let i = 0; i < n; i++) {
      const c = s.charCodeAt(i);
      if (c === 123) {
        stack.push(i);
      } else if (c === 125 && stack.length) {
        match[stack.pop()] = i;
      }
    }
  
    const root = { parts: [], start: 0, open: -1, alternatives: null };
    const frames = [root];
  
    for (let i = 0; i < n; i++) {
      const frame = frames[frames.length - 1];
      const c = s.charCodeAt(i);
  
      if (c === 123 && match[i] !== -1) {
        if (frame.start < i) frame.parts.push(s.slice(frame.start, i));
        frames.push({ parts: [], start: i + 1, open: i, alternatives: null });
      } else if (c === 44 && frame.open !== -1) {
        if (frame.start < i) frame.parts.push(s.slice(frame.start, i));
        if (frame.alternatives === null) frame.alternatives = [];
        frame.alternatives.push(frame.parts);
        frame.parts = [];
        frame.start = i + 1;
      } else if (c === 125 && frame.open !== -1 && match[frame.open] === i) {
        if (frame.start < i) frame.parts.push(s.slice(frame.start, i));
        frames.pop();
  
        const parent = frames[frames.length - 1];
        if (frame.alternatives === null) {
          parent.parts.push("{");
          for (let j = 0; j < frame.parts.length; j++) {
            parent.parts.push(frame.parts[j]);
          }
          parent.parts.push("}");
        } else {
          frame.alternatives.push(frame.parts);
          parent.parts.push(frame.alternatives);
        }
        parent.start = i + 1;
      }
    }
    if (root.start < n) root.parts.push(s.slice(root.start));
  
    // Compile the expression into a sequence of literals and choice points.
    // Each alternative ends with a jump to the continuation.
    const code = [];
  
    function compile(parts) {
      let pending = "";
      function flush() {
        if (pending) {
          code.push(pending);
          pending = "";
        }
      }
  
      for (let i = 0; i < parts.length; i++) {
        const part = parts[i];
        if (typeof part === "string") {
          pending += part;
        } else {
          flush();
          const choice = { branches: [] };
          code.push(choice);
          const jumps = [];
  
          for (let j = 0; j < part.length; j++) {
            choice.branches.push(code.length);
            compile(part[j]);
            if (j + 1 < part.length) {
              const jump = { target: 0 };
              jumps.push(jump);
              code.push(jump);
            }
          }
          const end = code.length;
          for (let j = 0; j < jumps.length; j++) jumps[j].target = end;
        }
      }
      flush();
    }
  
    compile(root.parts);
  
    const results = [];
    const pieces = [];
    const choices = [];
    let pc = 0;
  
    while (true) {
      while (pc < code.length) {
        const instruction = code[pc];
        if (typeof instruction === "string") {
          pieces.push(instruction);
          pc++;
        } else if (instruction.branches) {
          const branches = instruction.branches;
          if (branches.length > 1) {
            choices.push({ branches, next: 1, length: pieces.length });
          }
          pc = branches[0];
        } else {
          pc = instruction.target;
        }
      }
  
      results.push(pieces.join(""));
  
      while (choices.length) {
        const choice = choices[choices.length - 1];
        pieces.length = choice.length;
        pc = choice.branches[choice.next++];
        if (choice.next === choice.branches.length) choices.pop();
        break;
      }
      if (!choices.length && pc >= code.length) break;
    }
  
    return results;
  }

• 第 3 名MoonshotAI Kimi K2.7 Code未解决 · 通过 0/22 个测试生成耗时 27 秒 · $0.02

  回复被截断，代码不完整

  ✗	brace_expand("a{b,c}d")预期 ["abd", "acd"]回复中无代码	—
  ✗	brace_expand("{a,b}{c,d}")预期 ["ac", "ad", "bc", "bd"]回复中无代码	—
  ✗	brace_expand("{a}")预期 ["{a}"]回复中无代码	—

  ✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码⏱ 回复中无代码⏱ 回复中无代码⏱ 回复中无代码
• 第 3 名SpaceXAI Grok 4.7未解决 · 通过 0/22 个测试生成耗时 120 秒

  回复中无代码

  ✗	brace_expand("a{b,c}d")预期 ["abd", "acd"]回复中无代码	—
  ✗	brace_expand("{a,b}{c,d}")预期 ["ac", "ad", "bc", "bd"]回复中无代码	—
  ✗	brace_expand("{a}")预期 ["{a}"]回复中无代码	—

  ✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码✗ 回复中无代码⏱ 回复中无代码⏱ 回复中无代码⏱ 回复中无代码

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