POJ 3159 最短路 SPFA
#include<iostream>
using namespace std;
const int nMax = 30005;
const int mMax = 150005;
const int inf = 1000000000;
struct node{
int v, w, next;
}edge[mMax];
int n, edgeHead[nMax], dict[nMax];
int stack[nMax];
bool vis[nMax];
void spfa(){
for(int i = 2; i <= n; i ++)
dict[i] = inf;
dict[1] = 0;
int top = 0; // spfa的堆栈实现模板。
stack[++ top] = 1;
vis[1] = true;
while(top){
int u = stack[top --];
for(int p = edgeHead[u]; p != 0; p = edge[p].next){
int v = edge[p].v;
if(dict[v] > dict[u] + edge[p].w){
dict[v] = dict[u] + edge[p].w;
if(!vis[v]){
vis[v] = true;
stack[++ top] = v;
}
}
}
vis[u] = false;
}
}
int main(){
int m, i;
scanf("%d%d", &n, &m);
int k = 1;
while(m --){
int u, v, w;
scanf("%d%d%d", &u, &v, &w);
edge[k].v = v;
edge[k].w = w;
edge[k].next = edgeHead[u];
edgeHead[u] = k ++;
}
spfa();
printf("%d\n", dict[n]);
return 0;
}