算法总结——spfa（使用优先队列的dijkstra算法）

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<functional>//greater 使得从小到大  ，less反
//priority_queue<int, vector<int>, less<int> > que 相当于 priority_queue<int> que
#include<queue>
using namespace std;

const int MAX = 100;
const int inf = 0x3f3f3f3f;
struct edge{
    int to, cost;
}
typedef pair<int, int> P;
int V;
vector<edge> G[MAX];
int d[MAX];//距s的距离
void dijkstra(int s)
{
    priority_queue<P, vector<P>, greater<P> > que;
    fill(d, d + V, inf);
    d[s] = 0;
    que.push(P(0, s));
    while(!que.empty()){
        P p = que.top();
        que.pop();
        int v = p.second;
        if(d[v] < p.first) continue;//小优化
        for(int i = 0; i < G[v].size(); i++){
            edge e = G[v][i];
            if(d[e.to] > d[v] + e.cost){
                d[e.to] = d[v] + e.cost;
                que.push(P(d[e.to], e.to));
            }
        }
    }
}