Task · data processing medium JavaScript ·

Bank ledger

Process bank operations in order and return the final balances. Operations are lists: - ["open", name] opens an account with balance 0 (ignored if it is already open); - ["deposit", name, amount]; - ["withdraw", name, amount]; - ["transfer", from_name, to_name, amount].

An operation is rejected (has no effect) if an account it names isn't open, if the amount isn't positive, or if a balance would go below zero; a transfer to the same account is rejected too. Return a dictionary of every open account's name to its balance.

Signature

/**
 * @param {Array[]} ops
 * @returns {Object<string, number>}
 */
function balances(ops)

Examples

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])  // -> {"ann": 70, "bob": 30}

Plus 9 hidden tests and 1 large-input test under a time limit; their inputs are not shown. Tasks are given to the models in English.

#1MiniMax M3.1 Flashsolved · 11 of 11 testsanswer in 2.1 s · runtime 477 ms · $0.0003

✓

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])expected {"ann": 70, "bob": 30}

3 ms

✓ 3 ms✓ <1 ms✓ 1 ms✓ <1 ms✓ <1 ms✓ 2 ms✓ 4 ms✓ <1 ms✓ <1 ms⏱ 460 ms

Code

function balances(ops) {
  const accounts = Object.create(null);

  for (let i = 0; i < ops.length; i++) {
    const op = ops[i];
    const type = op[0];

    if (type === "open") {
      const name = op[1];
      if (!Object.prototype.hasOwnProperty.call(accounts, name)) {
        accounts[name] = 0;
      }
      continue;
    }

    if (type === "deposit" || type === "withdraw") {
      const name = op[1];
      const amount = op[2];

      if (!Object.prototype.hasOwnProperty.call(accounts, name)) continue;
      if (!(amount > 0)) continue;

      if (type === "deposit") {
        accounts[name] += amount;
      } else {
        if (accounts[name] < amount) continue;
        accounts[name] -= amount;
      }
      continue;
    }

    if (type === "transfer") {
      const from = op[1];
      const to = op[2];
      const amount = op[3];

      if (!Object.prototype.hasOwnProperty.call(accounts, from)) continue;
      if (!Object.prototype.hasOwnProperty.call(accounts, to)) continue;
      if (from === to) continue;
      if (!(amount > 0)) continue;
      if (accounts[from] < amount) continue;

      accounts[from] -= amount;
      accounts[to] += amount;
    }
  }

  return accounts;
}

#1Google Gemini 3.8 Flashsolved · 11 of 11 testsanswer in 5.8 s · runtime 493 ms · $0.0041

✓

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])expected {"ann": 70, "bob": 30}

2 ms

✓ 2 ms✓ 1 ms✓ 1 ms✓ <1 ms✓ 1 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ 2 ms⏱ 480 ms

Code

/**
 * @param {Array[]} ops
 * @returns {Object<string, number>}
 */
function balances(ops) {
  const accounts = new Map();

  for (let i = 0; i < ops.length; i++) {
    const op = ops[i];
    const type = op[0];

    if (type === "open") {
      const name = op[1];
      if (!accounts.has(name)) {
        accounts.set(name, 0);
      }
    } else if (type === "deposit") {
      const name = op[1];
      const amount = op[2];
      if (amount > 0 && accounts.has(name)) {
        accounts.set(name, accounts.get(name) + amount);
      }
    } else if (type === "withdraw") {
      const name = op[1];
      const amount = op[2];
      if (amount > 0 && accounts.has(name)) {
        const bal = accounts.get(name);
        if (bal >= amount) {
          accounts.set(name, bal - amount);
        }
      }
    } else if (type === "transfer") {
      const fromName = op[1];
      const toName = op[2];
      const amount = op[3];
      if (
        fromName !== toName &&
        amount > 0 &&
        accounts.has(fromName) &&
        accounts.has(toName)
      ) {
        const fromBal = accounts.get(fromName);
        if (fromBal >= amount) {
          accounts.set(fromName, fromBal - amount);
          accounts.set(toName, accounts.get(toName) + amount);
        }
      }
    }
  }

  const result = {};
  for (const [name, bal] of accounts) {
    result[name] = bal;
  }
  return result;
}

#1DeepSeek V4.1 Flashsolved · 11 of 11 testsanswer in 750 ms · runtime 537 ms · $0.0003

✓

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])expected {"ann": 70, "bob": 30}

3 ms

✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ <1 ms⏱ 527 ms

Code

function balances(ops) {
  const accounts = Object.create(null);
  const has = (name) => Object.prototype.hasOwnProperty.call(accounts, name);

  for (let i = 0; i < ops.length; i++) {
    const op = ops[i];
    const type = op[0];
    if (type === "open") {
      const name = op[1];
      if (!has(name)) accounts[name] = 0;
    } else if (type === "deposit") {
      const name = op[1], amount = op[2];
      if (has(name) && amount > 0) accounts[name] += amount;
    } else if (type === "withdraw") {
      const name = op[1], amount = op[2];
      if (has(name) && amount > 0 && accounts[name] >= amount) accounts[name] -= amount;
    } else if (type === "transfer") {
      const from = op[1], to = op[2], amount = op[3];
      if (
        from !== to &&
        has(from) &&
        has(to) &&
        amount > 0 &&
        accounts[from] >= amount
      ) {
        accounts[from] -= amount;
        accounts[to] += amount;
      }
    }
  }

  return Object.assign({}, accounts);
}

#1OpenAI GPT-6 Lunasolved · 11 of 11 testsanswer in 2.7 s · runtime 552 ms · $0.0002

✓

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])expected {"ann": 70, "bob": 30}

4 ms

✓ 1 ms✓ 3 ms✓ 2 ms✓ 2 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ <1 ms✓ 1 ms⏱ 534 ms

Code

function balances(ops) {
  const accounts = new Map();

  for (const op of ops) {
    const type = op[0];

    if (type === "open") {
      if (!accounts.has(op[1])) accounts.set(op[1], 0);
    } else if (type === "deposit") {
      const name = op[1], amount = op[2];
      if (accounts.has(name) && amount > 0) {
        accounts.set(name, accounts.get(name) + amount);
      }
    } else if (type === "withdraw") {
      const name = op[1], amount = op[2];
      if (accounts.has(name) && amount > 0 && accounts.get(name) >= amount) {
        accounts.set(name, accounts.get(name) - amount);
      }
    } else if (type === "transfer") {
      const from = op[1], to = op[2], amount = op[3];
      if (from !== to && amount > 0 && accounts.has(from) && accounts.has(to) &&
          accounts.get(from) >= amount) {
        accounts.set(from, accounts.get(from) - amount);
        accounts.set(to, accounts.get(to) + amount);
      }
    }
  }

  return Object.fromEntries(accounts);
}

Tokens cost: $0.0048 · How rounds are run and scored →

Bank ledger

Signature

/**
 * @param {Array[]} ops
 * @returns {Object<string, number>}
 */
function balances(ops)

Examples

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])  // -> {"ann": 70, "bob": 30}

Plus 9 hidden tests and 1 large-input test under a time limit; their inputs are not shown. Tasks are given to the models in English.

#1MiniMax M3.1 Flashsolved · 11 of 11 testsanswer in 2.1 s · runtime 477 ms · $0.0003

✓

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])expected {"ann": 70, "bob": 30}

3 ms

✓ 3 ms✓ <1 ms✓ 1 ms✓ <1 ms✓ <1 ms✓ 2 ms✓ 4 ms✓ <1 ms✓ <1 ms⏱ 460 ms

Code

function balances(ops) {
  const accounts = Object.create(null);

  for (let i = 0; i < ops.length; i++) {
    const op = ops[i];
    const type = op[0];

    if (type === "open") {
      const name = op[1];
      if (!Object.prototype.hasOwnProperty.call(accounts, name)) {
        accounts[name] = 0;
      }
      continue;
    }

    if (type === "deposit" || type === "withdraw") {
      const name = op[1];
      const amount = op[2];

      if (!Object.prototype.hasOwnProperty.call(accounts, name)) continue;
      if (!(amount > 0)) continue;

      if (type === "deposit") {
        accounts[name] += amount;
      } else {
        if (accounts[name] < amount) continue;
        accounts[name] -= amount;
      }
      continue;
    }

    if (type === "transfer") {
      const from = op[1];
      const to = op[2];
      const amount = op[3];

      if (!Object.prototype.hasOwnProperty.call(accounts, from)) continue;
      if (!Object.prototype.hasOwnProperty.call(accounts, to)) continue;
      if (from === to) continue;
      if (!(amount > 0)) continue;
      if (accounts[from] < amount) continue;

      accounts[from] -= amount;
      accounts[to] += amount;
    }
  }

  return accounts;
}

#1Google Gemini 3.8 Flashsolved · 11 of 11 testsanswer in 5.8 s · runtime 493 ms · $0.0041

✓

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])expected {"ann": 70, "bob": 30}

2 ms

✓ 2 ms✓ 1 ms✓ 1 ms✓ <1 ms✓ 1 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ 2 ms⏱ 480 ms

Code

/**
 * @param {Array[]} ops
 * @returns {Object<string, number>}
 */
function balances(ops) {
  const accounts = new Map();

  for (let i = 0; i < ops.length; i++) {
    const op = ops[i];
    const type = op[0];

    if (type === "open") {
      const name = op[1];
      if (!accounts.has(name)) {
        accounts.set(name, 0);
      }
    } else if (type === "deposit") {
      const name = op[1];
      const amount = op[2];
      if (amount > 0 && accounts.has(name)) {
        accounts.set(name, accounts.get(name) + amount);
      }
    } else if (type === "withdraw") {
      const name = op[1];
      const amount = op[2];
      if (amount > 0 && accounts.has(name)) {
        const bal = accounts.get(name);
        if (bal >= amount) {
          accounts.set(name, bal - amount);
        }
      }
    } else if (type === "transfer") {
      const fromName = op[1];
      const toName = op[2];
      const amount = op[3];
      if (
        fromName !== toName &&
        amount > 0 &&
        accounts.has(fromName) &&
        accounts.has(toName)
      ) {
        const fromBal = accounts.get(fromName);
        if (fromBal >= amount) {
          accounts.set(fromName, fromBal - amount);
          accounts.set(toName, accounts.get(toName) + amount);
        }
      }
    }
  }

  const result = {};
  for (const [name, bal] of accounts) {
    result[name] = bal;
  }
  return result;
}

#1DeepSeek V4.1 Flashsolved · 11 of 11 testsanswer in 750 ms · runtime 537 ms · $0.0003

✓

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])expected {"ann": 70, "bob": 30}

3 ms

✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ <1 ms⏱ 527 ms

Code

function balances(ops) {
  const accounts = Object.create(null);
  const has = (name) => Object.prototype.hasOwnProperty.call(accounts, name);

  for (let i = 0; i < ops.length; i++) {
    const op = ops[i];
    const type = op[0];
    if (type === "open") {
      const name = op[1];
      if (!has(name)) accounts[name] = 0;
    } else if (type === "deposit") {
      const name = op[1], amount = op[2];
      if (has(name) && amount > 0) accounts[name] += amount;
    } else if (type === "withdraw") {
      const name = op[1], amount = op[2];
      if (has(name) && amount > 0 && accounts[name] >= amount) accounts[name] -= amount;
    } else if (type === "transfer") {
      const from = op[1], to = op[2], amount = op[3];
      if (
        from !== to &&
        has(from) &&
        has(to) &&
        amount > 0 &&
        accounts[from] >= amount
      ) {
        accounts[from] -= amount;
        accounts[to] += amount;
      }
    }
  }

  return Object.assign({}, accounts);
}

#1OpenAI GPT-6 Lunasolved · 11 of 11 testsanswer in 2.7 s · runtime 552 ms · $0.0002

✓

balances([["open", "ann"], ["open", "bob"], ["deposit", "ann", 100], ["transfer", "ann", "bob", 30], ["withdraw", "bob", 50]])expected {"ann": 70, "bob": 30}

4 ms

✓ 1 ms✓ 3 ms✓ 2 ms✓ 2 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ <1 ms✓ 1 ms⏱ 534 ms

Code

function balances(ops) {
  const accounts = new Map();

  for (const op of ops) {
    const type = op[0];

    if (type === "open") {
      if (!accounts.has(op[1])) accounts.set(op[1], 0);
    } else if (type === "deposit") {
      const name = op[1], amount = op[2];
      if (accounts.has(name) && amount > 0) {
        accounts.set(name, accounts.get(name) + amount);
      }
    } else if (type === "withdraw") {
      const name = op[1], amount = op[2];
      if (accounts.has(name) && amount > 0 && accounts.get(name) >= amount) {
        accounts.set(name, accounts.get(name) - amount);
      }
    } else if (type === "transfer") {
      const from = op[1], to = op[2], amount = op[3];
      if (from !== to && amount > 0 && accounts.has(from) && accounts.has(to) &&
          accounts.get(from) >= amount) {
        accounts.set(from, accounts.get(from) - amount);
        accounts.set(to, accounts.get(to) + amount);
      }
    }
  }

  return Object.fromEntries(accounts);
}