（重刷）HDU 1874 畅通工程续 + HDU 2544 最短路 最短路水题，dijkstra解法。

#include <cstdio>

#define MAXN 200
#define INF 0xfffff

int n;
int Edge[MAXN][MAXN];
int s[MAXN];
int dist[MAXN];
int path[MAXN];

void Dijkstra(int v0) {
int i, j, k;
for (i = 0; i < n; i++) {
dist[i] = Edge[v0][i];
s[i] = 0;
if (i != v0 && INF > dist[i])
path[i] = v0;
else
path[i] = -1;
}
s[v0] = 1;
dist[v0] = 0;
for (i = 0; i < n - 1; i++) {
int min = INF, u = v0;
for (j = 0; j < n; j++)
if (!s[j] && dist[j] < min){
u = j;
min = dist[j];
}//if
s[u] = 1;
for (k = 0; k < n; k++) {
if (!s[k] && Edge[u][k] < INF && dist[u] + Edge[u] [k] < dist[k]) {
dist[k] = dist[u] + Edge[u][k];
path[k] = u;
}//if
}//for
}//for
}

int main() {
int m;
int i, j;
while (scanf("%d%d", &n, &m) != EOF) {
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
if (i == j)
Edge[i][j] = 0;
else
Edge[i][j] = INF;
int x, y, z;
for (i = 0; i < m; i++) {
scanf("%d%d%d", &x, &y, &z);
if (z < Edge[x][y])
Edge[y][x] = Edge[x][y] = z;
}
scanf("%d%d", &x, &y);
Dijkstra(x);
if (dist[y] < INF)
printf("%d\n", dist[y]);
else
printf("-1\n");
}//while
return 0;
}

#include <cstdio>

#define MAXN 200
#define INF 0xfffff

int n;
int Edge[MAXN][MAXN];
int s[MAXN];
int dist[MAXN];
int path[MAXN];

void Dijkstra(int v0) {
int i, j, k;
for (i = 0; i < n; i++) {
dist[i] = Edge[v0][i];
s[i] = 0;
if (i != v0 && INF > dist[i])
path[i] = v0;
else
path[i] = -1;
}
s[v0] = 1;
dist[v0] = 0;
for (i = 0; i < n - 1; i++) {
int min = INF, u = v0;
for (j = 0; j < n; j++)
if (!s[j] && dist[j] < min){
u = j;
min = dist[j];
}//if
s[u] = 1;
for (k = 0; k < n; k++) {
if (!s[k] && Edge[u][k] < INF && dist[u] + Edge[u] [k] < dist[k]) {
dist[k] = dist[u] + Edge[u][k];
path[k] = u;
}//if
}//for
}//for
}

int main() {
int m;
int i, j;
while (scanf("%d%d", &n, &m) && n && m) {
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
if (i == j)
Edge[i][j] = 0;
else
Edge[i][j] = INF;
int x, y, z;
for (i = 0; i < m; i++) {
scanf("%d%d%d", &x, &y, &z);
if (z < Edge[x-1][y-1])
Edge[y-1][x-1] = Edge[x-1][y-1] = z;
}
Dijkstra(0);
printf("%d\n", dist[n - 1]);
}//while
return 0;
}