Tarea · cadenas de texto difícil Python ·
Longest repeated substring
Return the longest substring that occurs in s at least twice; the occurrences may overlap. If several substrings have that length, return the one whose first occurrence starts earliest. Return "" if no character repeats. s has lowercase letters only and can be up to 100,000 characters long.
Firma
def longest_repeat(s: str) -> str:Ejemplos
longest_repeat('banana') # -> 'ana'
longest_repeat('abcd') # -> ''
longest_repeat('aaaa') # -> 'aaa'Más 9 pruebas ocultas y 3 pruebas de carga bajo un límite de tiempo; sus entradas no se muestran. Las tareas se presentan a los modelos en inglés.
#1OpenAI GPT-6.1 Terraresuelto · 15 de 15 pruebasrespuesta en 6.0 s · ejecución 932 ms · $0.0021 ✓ longest_repeat('banana')esperado 'ana' <1 ms ✓ longest_repeat('abcd')esperado '' <1 ms ✓ longest_repeat('aaaa')esperado 'aaa' <1 ms ✓ <1 ms✓ <1 ms✓ 2 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms⏱ 449 ms⏱ 165 ms⏱ 310 msCódigo
def longest_repeat(s: str) -> str: n = len(s) if n < 2: return "" transitions = [{}] links = [-1] lengths = [0] first_pos = [-1] last = 0 for i, ch in enumerate(s): cur = len(links) transitions.append({}) lengths.append(lengths[last] + 1) links.append(0) first_pos.append(i) p = last while p >= 0 and ch not in transitions[p]: transitions[p][ch] = cur p = links[p] if p >= 0: q = transitions[p][ch] if lengths[p] + 1 == lengths[q]: links[cur] = q else: clone = len(links) transitions.append(transitions[q].copy()) lengths.append(lengths[p] + 1) links.append(links[q]) first_pos.append(first_pos[q]) while p >= 0 and transitions[p].get(ch) == q: transitions[p][ch] = clone p = links[p] links[q] = clone links[cur] = clone last = cur best_len = 0 best_start = n for state in range(1, len(links)): parent = links[state] length = lengths[parent] if length >= best_len and length: start = first_pos[parent] - length + 1 if length > best_len or start < best_start: best_len = length best_start = start return s[best_start:best_start + best_len] if best_len else ""#2DeepSeek V4.1 Flashno resuelto · 14 de 15 pruebasrespuesta en 1.9 s · ejecución 1.7 s · $0.0003 ✓ longest_repeat('banana')esperado 'ana' <1 ms ✓ longest_repeat('abcd')esperado '' <1 ms ✓ longest_repeat('aaaa')esperado 'aaa' <1 ms ✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ 2 ms✓ 1 ms✓ <1 ms✓ <1 ms✓ <1 ms⏱ 634 ms⏱ límite de tiempo superado⏱ 529 msCódigo
def longest_repeat(s: str) -> str: n = len(s) if n <= 1: return "" # build suffix array via prefix doubling sa = list(range(n)) rank = [ord(c) for c in s] k = 1 tmp = [0] * n while True: sa.sort(key=lambda i: (rank[i], rank[i + k] if i + k < n else -1)) tmp[sa[0]] = 0 for idx in range(1, n): a = sa[idx - 1] b = sa[idx] ra = rank[a] rb = rank[b] if ra != rb: tmp[b] = tmp[a] + 1 else: ra2 = rank[a + k] if a + k < n else -1 rb2 = rank[b + k] if b + k < n else -1 tmp[b] = tmp[a] + (1 if ra2 != rb2 else 0) rank, tmp = tmp, rank if rank[sa[-1]] == n - 1: break k <<= 1 # kasai LCP lcp = [0] * n p = [0] * n for i in range(n): p[sa[i]] = i h = 0 for i in range(n): r = p[i] if r > 0: j = sa[r - 1] while i + h < n and j + h < n and s[i + h] == s[j + h]: h += 1 lcp[r] = h if h: h -= 1 else: h = 0 best_len = 0 best_pos = 0 for r in range(1, n): l = lcp[r] if l > best_len: best_len = l best_pos = sa[r - 1] if sa[r - 1] < sa[r] else sa[r] elif l == best_len and l > 0: pos = sa[r - 1] if sa[r - 1] < sa[r] else sa[r] if pos < best_pos: best_pos = pos return s[best_pos:best_pos + best_len] if best_len > 0 else ""Segundo intento
no resuelto · 14 de 15 pruebasrespuesta en 2.0 s · $0.0006El modelo vio cuántos tests fallaron, los ejemplos fallidos con los valores esperados y devueltos, y solo el motivo por el que fallaron los tests ocultos, no sus entradas. No cuenta para las posiciones ni para el rating.
✓ longest_repeat('banana')esperado 'ana' 2 ms ✓ longest_repeat('abcd')esperado '' <1 ms ✓ longest_repeat('aaaa')esperado 'aaa' <1 ms ✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms⏱ 825 ms⏱ límite de tiempo superado⏱ 624 msCódigo
def longest_repeat(s: str) -> str: n = len(s) if n <= 1: return "" # Build suffix array using prefix doubling with counting sort (radix sort) sa = list(range(n)) rank = [ord(c) for c in s] k = 1 tmp = [0] * n while True: # Sort by (rank[i], rank[i+k]) using counting sort max_rank = max(rank) + 1 # Second key sort key2 = [rank[i + k] + 1 if i + k < n else 0 for i in range(n)] cnt = [0] * (max_rank + 1) for v in key2: cnt[v] += 1 for i in range(1, len(cnt)): cnt[i] += cnt[i - 1] sa2 = [0] * n for i in range(n - 1, -1, -1): v = key2[i] cnt[v] -= 1 sa2[cnt[v]] = i # First key sort key1 = [rank[i] for i in range(n)] cnt = [0] * max_rank for i in range(n): cnt[key1[sa2[i]]] += 1 for i in range(1, max_rank): cnt[i] += cnt[i - 1] for i in range(n - 1, -1, -1): v = key1[sa2[i]] cnt[v] -= 1 sa[cnt[v]] = sa2[i] # Reassign ranks tmp[sa[0]] = 0 for idx in range(1, n): a = sa[idx - 1] b = sa[idx] ra = rank[a] rb = rank[b] if ra != rb: tmp[b] = tmp[a] + 1 else: ra2 = rank[a + k] if a + k < n else -1 rb2 = rank[b + k] if b + k < n else -1 tmp[b] = tmp[a] + (1 if ra2 != rb2 else 0) rank, tmp = tmp, rank if rank[sa[-1]] == n - 1: break k <<= 1 # Kasai LCP lcp = [0] * n p = [0] * n for i in range(n): p[sa[i]] = i h = 0 for i in range(n): r = p[i] if r > 0: j = sa[r - 1] while i + h < n and j + h < n and s[i + h] == s[j + h]: h += 1 lcp[r] = h if h: h -= 1 else: h = 0 best_len = 0 best_pos = 0 for r in range(1, n): l = lcp[r] if l > best_len: best_len = l best_pos = sa[r - 1] if sa[r - 1] < sa[r] else sa[r] elif l == best_len and l > 0: pos = sa[r - 1] if sa[r - 1] < sa[r] else sa[r] if pos < best_pos: best_pos = pos return s[best_pos:best_pos + best_len] if best_len > 0 else ""#2Anthropic Claude Opus 5.5no resuelto · 14 de 15 pruebasrespuesta en 15 s · ejecución 1.8 s · $0.03 ✓ longest_repeat('banana')esperado 'ana' <1 ms ✓ longest_repeat('abcd')esperado '' <1 ms ✓ longest_repeat('aaaa')esperado 'aaa' <1 ms ✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms✓ <1 ms⏱ 951 ms⏱ 117 ms⏱ límite de tiempo superadoCódigo
import random def longest_repeat(s: str) -> str: n = len(s) if n < 2: return "" M = (1 << 61) - 1 B = random.randrange(10**6, 10**9) H = [0] * (n + 1) P = [1] * (n + 1) h = 0 p = 1 for i, c in enumerate(s): h = (h * B + ord(c)) % M H[i + 1] = h p = p * B % M P[i + 1] = p def hashes(L): pl = P[L] return [(H[i + L] - H[i] * pl) % M for i in range(n - L + 1)] def ok(L): hs = hashes(L) return len(set(hs)) < len(hs) lo, hi = 0, n - 1 while lo < hi: mid = (lo + hi + 1) // 2 if ok(mid): lo = mid else: hi = mid - 1 L = lo if L == 0: return "" hs = hashes(L) seen = {} best = n for i, x in enumerate(hs): j = seen.get(x) if j is None: seen[x] = i elif j < best: best = j return s[best:best + L]Segundo intento
no resuelto · 14 de 15 pruebasrespuesta en 19 s · $0.04El modelo vio cuántos tests fallaron, los ejemplos fallidos con los valores esperados y devueltos, y solo el motivo por el que fallaron los tests ocultos, no sus entradas. No cuenta para las posiciones ni para el rating.
✓ longest_repeat('banana')esperado 'ana' 3 ms ✓ longest_repeat('abcd')esperado '' 2 ms ✓ longest_repeat('aaaa')esperado 'aaa' 3 ms ✓ 2 ms✓ 2 ms✓ 2 ms✓ <1 ms✓ 3 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ <1 ms⏱ 543 ms⏱ límite de tiempo superado⏱ 445 msCódigo
import random def longest_repeat(s: str) -> str: n = len(s) if n < 2: return "" M = (1 << 61) - 1 B = random.randrange(10**6, 10**9) H = [0] * (n + 1) P = [1] * (n + 1) h = 0 p = 1 i = 1 for c in s.encode(): h = (h * B + c) % M H[i] = h p = p * B % M P[i] = p i += 1 def hashes(L): pl = P[L] return [(a - b * pl) % M for a, b in zip(H[L:], H)] def ok(L): if L <= 0: return True if L >= n: return False hs = hashes(L) return len(set(hs)) < len(hs) # galloping search lo = 0 step = 1 hi = None while True: cand = lo + step if cand >= n: hi = n - 1 break if ok(cand): lo = cand step *= 2 else: hi = cand - 1 break while lo < hi: mid = (lo + hi + 1) // 2 if ok(mid): lo = mid else: hi = mid - 1 L = lo if L == 0: return "" hs = hashes(L) seen = {} best = n for i, x in enumerate(hs): j = seen.get(x) if j is None: seen[x] = i elif j < best: best = j return s[best:best + L]#4SpaceXAI Grok Build 0.1no resuelto · 12 de 15 pruebasrespuesta en 62 s · ejecución 2.4 s · $0.02 ✓ longest_repeat('banana')esperado 'ana' <1 ms ✓ longest_repeat('abcd')esperado '' 2 ms ✓ longest_repeat('aaaa')esperado 'aaa' <1 ms ✓ 3 ms✓ 1 ms✓ 1 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ 1 ms✓ <1 ms✓ 1 ms⏱ límite de tiempo superado⏱ límite de tiempo superado⏱ límite de tiempo superadoCódigo
def longest_repeat(s: str) -> str: n = len(s) if n <= 1: return "" sa = list(range(n)) rank = [ord(c) for c in s] tmp = [0] * n k = 1 while k < n: sa.sort(key=lambda x: (rank[x], rank[x + k] if x + k < n else -1)) tmp[sa[0]] = 0 for i in range(1, n): prev = sa[i - 1] curr = sa[i] prev_key = (rank[prev], rank[prev + k] if prev + k < n else -1) curr_key = (rank[curr], rank[curr + k] if curr + k < n else -1) tmp[curr] = tmp[prev] + (1 if prev_key < curr_key else 0) rank = tmp[:] k <<= 1 rnk = [0] * n for i in range(n): rnk[sa[i]] = i lcp = [0] * n h = 0 for i in range(n): if rnk[i] == n - 1: h = 0 continue j = sa[rnk[i] + 1] while i + h < n and j + h < n and s[i + h] == s[j + h]: h += 1 lcp[rnk[i]] = h if h > 0: h -= 1 max_l = max(lcp) if lcp else 0 if max_l == 0: return "" min_start = n for i in range(n - 1): if lcp[i] == max_l: start1 = sa[i] start2 = sa[i + 1] min_start = min(min_start, start1, start2) return s[min_start:min_start + max_l]Segundo intento
no resuelto · 13 de 15 pruebasrespuesta en 40 s · $0.02El modelo vio cuántos tests fallaron, los ejemplos fallidos con los valores esperados y devueltos, y solo el motivo por el que fallaron los tests ocultos, no sus entradas. No cuenta para las posiciones ni para el rating.
✓ longest_repeat('banana')esperado 'ana' <1 ms ✓ longest_repeat('abcd')esperado '' <1 ms ✓ longest_repeat('aaaa')esperado 'aaa' 2 ms ✓ <1 ms✓ <1 ms✓ <1 ms✓ 1 ms✓ 1 ms✓ 2 ms✓ 3 ms✓ <1 ms✓ <1 ms⏱ límite de tiempo superado⏱ 100 ms⏱ límite de tiempo superadoCódigo
from collections import defaultdict def longest_repeat(s: str) -> str: n = len(s) if n <= 1: return "" MOD1 = 10**9 + 7 MOD2 = 10**9 + 9 BASE1 = 131 BASE2 = 137 pow1 = [1] * (n + 1) pow2 = [1] * (n + 1) pre1 = [0] * (n + 1) pre2 = [0] * (n + 1) for i in range(n): pow1[i + 1] = pow1[i] * BASE1 % MOD1 pow2[i + 1] = pow2[i] * BASE2 % MOD2 pre1[i + 1] = (pre1[i] * BASE1 + ord(s[i])) % MOD1 pre2[i + 1] = (pre2[i] * BASE2 + ord(s[i])) % MOD2 def get_h1(l, r): val = (pre1[r] - pre1[l] * pow1[r - l] % MOD1 + MOD1) % MOD1 return val def get_h2(l, r): val = (pre2[r] - pre2[l] * pow2[r - l] % MOD2 + MOD2) % MOD2 return val max_L = 0 low = 1 high = n - 1 while low <= high: mid = (low + high) // 2 seen = set() has = False for i in range(n - mid + 1): h1 = get_h1(i, i + mid) h2 = get_h2(i, i + mid) key = (h1, h2) if key in seen: has = True break seen.add(key) if has: max_L = mid low = mid + 1 else: high = mid - 1 if max_L == 0: return "" pos = defaultdict(list) for i in range(n - max_L + 1): h1 = get_h1(i, i + max_L) h2 = get_h2(i, i + max_L) key = (h1, h2) pos[key].append(i) min_start = n for lst in pos.values(): if len(lst) >= 2: min_start = min(min_start, lst[0]) return s[min_start:min_start + max_L]
Coste en tokens: $0.11 · Cómo se ejecutan y puntúan las rondas →