HDU2433 Travel BFS求最短路徑樹+最佳化

/*1750ms邊長為1，所以用BFS求最短路對於每一個點，做一次BFS，求出以這個點為出發點時的最短路徑樹的長度和它包含的邊記錄長度是用於求值，記錄邊是用於最佳化。因為只有處於最短路徑樹上的邊的改動才會影響到結果如果要去的邊的不在最短路徑樹上，不影響結果，如果在，則重新計算最佳化後還是逾時，網上的解題報告都說用short，還是跑了1750ms，可能這題用vector來儲存不太合適*/#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);}}}