[hiho 23]单源最短路-Dijstra算法

#include <stdio.h>
#include <string.h>
#include <algorithm>

#define N 1005

unsigned w

;

int main(){
memset(w, -1, sizeof(w));
int n, m, u, v;
scanf("%d%d%d%d", &n, &m, &u, &v);
int from, to;
unsigned weight;
for (int i = 0; i < m; i++) {
scanf("%d%d%u", &from, &to, &weight);
weight = std::min(weight, w[from][to]);
w[from][to] = w[to][from] = weight;
}
int min_idx;
unsigned min;
while (true) {
min_idx = 1;
min = w[u][1];
for (int i = 2; i <= n; i++) {
if (min > w[u][i]) {
min = w[u][i];
min_idx = i;
}
}
for (int i = 1; i <= n; i++) {
if (w[min_idx][i] != (unsigned)-1) {
w[u][i] = std::min(w[u][i], w[u][min_idx] + w[min_idx][i]);
}
}
if (min_idx == v) {
break;
} else {
w[u][min_idx] = -1;
}
}
printf("%u\n", w[u][v]);
return 0;
}