#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 ii[M], kk[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
ii[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, k, 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, &k), i--, j--, k--;
if (k == -1)
g = -1;
else
kk[g = m++] = k;
append(i, j, g), append(j, i, g);
}
dfs1(-1, s, 0);
dfs2(-1, s, 0);
if (bb[t] == 0) {
printf("%d\n", dd[t]);
return 0;
}
for (g = 0; g < m; g++)
dds[g] = dd[kk[g]];
dfs2(-1, t, 0);
for (g = 0; g < m; g++)
ddt[g] = dd[kk[g]];
for (g = 0; g < m; g++) {
dfs2(-1, kk[g], 0);
for (g_ = 0; g_ < m; g_++)
ddd[g][g_] = dd[kk[g_]];
}
for (b = 1; b < 1 << m; b++)
memset(dp[b], 0x3f, m * sizeof *dp[b]);
for (g = 0; g < m; g++)
if (bb[kk[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[kk[g_]] & b) == bb[kk[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
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, &k), i--, j--, k--;
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
340 KB |
Output is correct |
| 3 |
Correct |
73 ms |
11212 KB |
Output is correct |
| 4 |
Incorrect |
65 ms |
11108 KB |
Output isn't correct |
| 5 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
340 KB |
Output is correct |
| 2 |
Correct |
0 ms |
340 KB |
Output is correct |
| 3 |
Incorrect |
1 ms |
428 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
1 ms |
212 KB |
Output is correct |
| 2 |
Correct |
0 ms |
340 KB |
Output is correct |
| 3 |
Correct |
73 ms |
11212 KB |
Output is correct |
| 4 |
Incorrect |
65 ms |
11108 KB |
Output isn't correct |
| 5 |
Halted |
0 ms |
0 KB |
- |
