HDU 3986 最短路（点点之间多条边）删除边后求最短

#include<iostream>#include<algorithm>#include<cstdio>#include<queue>using namespace std;#define manx 1009const int inf=99999999;int g[manx][manx],pre[manx];int n,m,dist[manx],sum;int g1[manx][manx];bool vist[manx];void dijkstra(){    for(int i=1;i<=n;i++){        dist[i]=g[1][i];        vist[i]=0;        pre[i]=1;    }    vist[1]=1; dist[1]=0;    for(int i=1;i<=n;i++){        int max = inf, k = -1;        for(int j=1;j<=n;j++){            if(!vist[j] && dist[j]<max)                max = dist[j], k = j;        }         if(k == -1) break;        vist[k] = 1;        for(int j=1;j<=n;j++){            if(!vist[j] && dist[j]>dist[k]+g[k][j]){                dist[j] = dist[k]+g[k][j];                pre[j] = k;            }               }    }}void init(int n){    for(int i=0;i<=n;i++)        for(int j=0;j<=n;j++){            g[i][j] = g1[i][j] = inf;        }    }void spfa(){    queue<int>que;    for(int i=1;i<=n;i++){        dist[i] = inf;        vist[i] = 0;    }    int v = 1;    vist[v] = 1;    dist[v] = 0;    que.push(v);    while(!que.empty()){        int u = que.front();        que.pop();        vist[u] = 0;        for(int i=1;i<=n;i++){            if(dist[i]>dist[u]+g[u][i]){                dist[i] = dist[u] + g[u][i];                if(!vist[i]){                vist[i] = 1;                que.push(i);                }                }               }    }}int main(){    int t;    scanf("%d",&t);    while(t--){    scanf("%d%d",&n,&m);        int a,b,c;        init(n);        for(int i=0;i<m;i++){            scanf("%d%d%d",&a,&b,&c);            if(g[a][b]>c){                 g1[a][b]=g1[b][a]=g[a][b];                g[a][b]=g[b][a]=c;            }                else if(g1[a][b]>c)            g1[a][b]=g1[b][a]=c;        }        dijkstra();        int ans = dist[n];        int x = n;        while(pre[x]!=x){            int val = g[x][pre[x]];            g[x][pre[x]] = g[pre[x]][x] = g1[pre[x]][x];            spfa();            if(ans>=inf) break;            ans = ans > dist[n] ? ans : dist[n];            g[x][pre[x]] = g[pre[x]][x] = val;            x = pre[x];        }        if(ans>=inf) printf("-1\n");        else  printf("%d\n",ans);    }}