POJ 2387Til the Cows Come Home(最短路)

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题目连接：http://poj.org/problem?id=2387

裸题最短路，不解释。。。dijkstra代码如下：

#include<iostream>#include<cstring>#include<cstdio>#include<algorithm>#include<queue>using namespace std;#define MAX 1005#define CLR(arr,v) memset(arr,v,sizeof(arr))int h[MAX],des[MAX*4],val[MAX*4],nex[MAX*4],dis[MAX],pos;int map[MAX][MAX];bool inque[MAX];struct edges{int end,value;bool operator<(const edges &ed) const{return value > ed.value;}}mid;priority_queue<edges> q;void add(int u,int v,int f){des[++pos] = v;val[pos] = f;nex[pos] = h[u];h[u] = pos;}void init(){pos = 0;   CLR(map,-1);CLR(h,0); CLR(nex,0);CLR(des,0);CLR(val,0);fill(dis,dis+MAX,INT_MAX);CLR(inque,0);while(!q.empty()) q.pop();}int Dijkstra(int n){dis[1] = 0;mid.end = 1;mid.value = 0;q.push(mid);inque[1] = true;while(!q.empty()){int st = q.top().end,cost = q.top().value;q.pop();inque[st] = false;for(int i = h[st]; i ;i = nex[i]){if(dis[ des[i] ] == INT_MAX || dis[st] + val[i] < dis[ des[i] ]){dis[ des[i] ] = dis[st] + val[i];if(!inque[ des[i] ]){mid.end = des[i];mid.value = dis[ des[i] ];q.push(mid);inque[ des[i] ] = true;}}}}return dis[n] == INT_MAX ? -1 : dis[n];}int main(){int n,m;while(~scanf("%d%d",&m,&n)){init();int u,v,f;for(int i = 0;i < m;++i){scanf("%d%d%d",&u,&v,&f);if(map[u][v] == -1 || f < map[u][v]){map[u][v] = map[v][u] = f;}}for(int i = 1;i <= n;++i)for(int j = 1;j <= n;++j)if(map[i][j] != -1)add(i,j,map[i][j]);printf("%d\n",Dijkstra(n));}return 0;}