HDU2433 Travel BFS求最短路径树+优化

/*1750ms边长为1，所以用BFS求最短路对于每一个点，做一次BFS，求出以这个点为出发点时的最短路径树的长度和它包含的边记录长度是用于求值，记录边是用于优化。因为只有处于最短路径树上的边的改动才会影响到结果如果要去的边的不在最短路径树上，不影响结果，如果在，则重新计算优化后还是超时，网上的解题报告都说用short，还是跑了1750ms，可能这题用vector来存储不太合适*/#include <iostream>#include <vector>#include <queue>using namespace std;#define MAX 105struct node{short start;short end;}E[3005];vector<vector<int> >V(MAX);short dis[MAX], vis[MAX];bool hash[MAX][3005];void BFS(short start, short edge);int main(){short n, m, i, j, k, a, b, ans, temp;bool flag;while(scanf("%hd%hd",&n,&m)!=EOF){flag = 1;for(i = 0; i <= n; i++)V[i].clear();memset(dis, 0, sizeof(dis));memset(hash, 0, sizeof(hash));for(i = 0; i < m; i++){scanf("%hd%hd",&a,&b);E[i].start = a;E[i].end = b;V[a].push_back(i);V[b].push_back(i);}for(i = 1; i <= n; i++){if(!flag)break;BFS(i, -1);if(i == 1){for(j = 1; j <= n; j++){if(vis[j] == 0){flag = 0;break;}}}for(j = 1; j <= n; j++)dis[i] = dis[i] + vis[j] - 1;}for(i = 0; i < m; i++){if(flag == 0){printf("INF\n");continue;}ans = 0;for(j = 1; j <= n; j++){if(ans == -1)break;if(hash[j][i] == 0)ans = ans + dis[j];else{temp = 0;BFS(j, i);for(k = 1; k <= n; k++){if(temp == -1)break;if(vis[k] == 0)temp = -1;else temp = temp + vis[k] - 1;}if(temp == -1)ans = -1;else ans = ans + temp;}}if(ans == -1)printf("INF\n");elseprintf("%hd\n",ans);}}return 0;}void BFS(short start,short edge){memset(vis, 0, sizeof(vis));int p, q, i;queue<int> Q;vis[start] = 1;Q.push(start);while(!Q.empty()){p = Q.front();Q.pop();for(i = 0; i < V[p].size(); i++){q = E[V[p][i]].start + E[V[p][i]].end - p;if(vis[q])continue;//if(edge!=-1 && ((E[edge].start==p&&E[edge].end==q)||(E[edge].start==q&&E[edge].end==p)))if(edge == V[p][i])continue;if(edge == -1)hash[start][V[p][i]] = 1;vis[q] = vis[p] + 1;Q.push(q);}}}