Submission #831414

#TimeUsernameProblemLanguageResultExecution timeMemory
831414rainboyLOSTIKS (INOI20_lostiks)C11
59 / 100
2047 ms114668 KiB
#include <stdio.h> #include <stdlib.h> #include <string.h> #define N 1000000 #define M 20 #define INF 0x3f3f3f3f int min(int a, int b) { return a < b ? a : b; } int n, m; int *ej[N], *eg[N], eo[N]; int uu[M], vv[M]; void append(int i, int j, int g) { int o = eo[i]++; if (o >= 2 && (o & o - 1) == 0) { ej[i] = (int *) realloc(ej[i], o * 2 * sizeof *ej[i]); eg[i] = (int *) realloc(eg[i], o * 2 * sizeof *eg[i]); } ej[i][o] = j, eg[i][o] = g; } int bb[N]; void dfs1(int p, int i, int b) { int o; bb[i] = b; for (o = eo[i]; o--; ) { int j = ej[i][o], g = eg[i][o]; if (j != p) { if (g == -1) dfs1(i, j, b); else vv[g] = i, dfs1(i, j, b | 1 << g); } } } int dd[N]; void dfs2(int p, int i, int d) { int o; dd[i] = d; for (o = eo[i]; o--; ) { int j = ej[i][o]; if (j != p) dfs2(i, j, d + 1); } } int main() { static int dds[M], ddt[M], ddd[M][M], dp[1 << M][M]; int g, g_, h, i, j, u, b, s, t, ans; scanf("%d%d%d", &n, &s, &t), s--, t--; for (i = 0; i < n; i++) { ej[i] = (int *) malloc(2 * sizeof *ej[i]); eg[i] = (int *) malloc(2 * sizeof *eg[i]); } m = 0; for (h = 0; h < n - 1; h++) { scanf("%d%d%d", &i, &j, &u), i--, j--, u--; if (u == -1) g = -1; else uu[g = m++] = u; append(i, j, g), append(j, i, g); } dfs1(-1, s, 0); if (bb[t] == 0) { dfs2(-1, s, 0); printf("%d\n", dd[t]); return 0; } for (g_ = 0; g_ < m; g_++) { dfs2(-1, uu[g_], 0); dds[g_] = dd[s] + dd[vv[g_]]; for (g = 0; g < m; g++) ddd[g][g_] = dd[vv[g]] + dd[vv[g_]]; } dfs2(-1, t, 0); for (g = 0; g < m; g++) ddt[g] = dd[vv[g]]; for (b = 1; b < 1 << m; b++) memset(dp[b], 0x3f, m * sizeof *dp[b]); for (g = 0; g < m; g++) if (bb[uu[g]] == 0 && bb[vv[g]] == 0) dp[1 << g][g] = dds[g]; ans = INF; for (b = 1; b < 1 << m; b++) for (g = 0; g < m; g++) { int x = dp[b][g]; if (x == INF) continue; if ((bb[t] & b) == bb[t]) ans = min(ans, x + ddt[g]); for (g_ = 0; g_ < m; g_++) if ((b & 1 << g_) == 0 && (bb[uu[g_]] & b) == bb[uu[g_]] && (bb[vv[g_]] & b) == bb[vv[g_]]) dp[b | 1 << g_][g_] = min(dp[b | 1 << g_][g_], x + ddd[g][g_]); } if (ans == INF) ans = -1; printf("%d\n", ans); return 0; }

Compilation message (stderr)

Main.c: In function 'append':
Main.c:19:23: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   19 |  if (o >= 2 && (o & o - 1) == 0) {
      |                     ~~^~~
Main.c: In function 'main':
Main.c:62:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   62 |  scanf("%d%d%d", &n, &s, &t), s--, t--;
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~
Main.c:69:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |   scanf("%d%d%d", &i, &j, &u), i--, j--, u--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~
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