Gym - 100625D Destination Unknown 最短路

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http://codeforces.com/gym/100625/attachments/download/3213/2013-benelux-algorithm-programming-contest-bapc-13-en.pdf

题意：给你一张无向图，t个可能的目的地，问在这t个点中哪些点的最短路中经过了g和h

思路：这是傻逼题，我直接dijstra用vector< set<int> > 保存路径，最后再去判断下。。好像这并不是出题者想要的解法，不过时间还可以，300+ms

  1 #pragma comment(linker, "/STACK:1000000000")  2 #include <iostream>  3 #include <cstdio>  4 #include <fstream>  5 #include <algorithm>  6 #include <cmath>  7 #include <deque>  8 #include <vector>  9 #include <queue> 10 #include <string> 11 #include <cstring> 12 #include <map> 13 #include <stack> 14 #include <set> 15 #define LL long long 16 #define MAXN 100005 17 #define INF 0x3f3f3f3f 18 #define eps 1e-8 19 using namespace std; 20 struct Edge 21 { 22     int from, to, dist; 23     Edge(int from, int to, int dist):from(from), to(to), dist(dist){}; 24 }; 25 struct HeapNode 26 { 27     int d, u; 28     HeapNode(int d, int u):d(d), u(u){}; 29     bool operator <(const HeapNode& rhs) const{ 30         return d > rhs.d; 31     } 32 }; 33 vector< set<int> > road[MAXN]; 34 struct Dijstra 35 { 36     int n, m; 37     vector<Edge> edges; 38     vector<int> G[MAXN]; 39     bool done[MAXN]; 40     int d[MAXN]; 41     int p[MAXN]; 42  43     void init(int n){ 44         this->n = n; 45         for(int i = 0; i <= n; i++){ 46             G[i].clear(); 47             road[i].clear(); 48         } 49         edges.clear(); 50     } 51  52     void AddEdge(int from, int to, int dist){ 53         edges.push_back(Edge(from, to, dist)); 54         m = edges.size(); 55         G[from].push_back(m - 1); 56     } 57  58     void dijstra(int s){ 59         priority_queue<HeapNode> Q; 60         for(int i = 0; i <= n; i++){ 61             d[i] = INF; 62         } 63         d[s] = 0; 64         memset(done, 0, sizeof(done)); 65         Q.push(HeapNode(0, s)); 66         while(!Q.empty()){ 67             HeapNode x = Q.top(); 68             Q.pop(); 69             int u = x.u; 70             if(done[u]) continue; 71             done[u]  = true; 72             for(int i = 0; i < G[u].size(); i++){ 73                 Edge& e = edges[G[u][i]]; 74                 if(d[e.to] > d[u] + e.dist){ 75                     d[e.to] = d[u] + e.dist; 76                     road[e.to].clear(); 77                     if(road[u].empty()){ 78                         set<int> tmp; 79                         tmp.clear(); 80                         tmp.insert(u); 81                         road[e.to].push_back(tmp); 82                     } 83                     else{ 84                         for(int j = 0; j < road[u].size(); j++){ 85                             road[e.to].push_back(road[u][j]); 86                             road[e.to][j].insert(u); 87                         } 88                     } 89                     p[e.to] = G[u][i]; 90                     Q.push(HeapNode(d[e.to], e.to)); 91                 } 92                 else if(d[e.to] == d[u] + e.dist){ 93                     int w = road[e.to].size(); 94                     for(int j = 0; j < road[u].size(); j++){ 95                         road[e.to].push_back(road[u][j]); 96                         road[e.to][w + j].insert(u); 97                     } 98                 } 99             }100         }101     }102 };103 int n, m, t, g, h, s;104 Dijstra p;105 vector<int> res;106 int main()107 {108 #ifndef ONLINE_JUDGE109     freopen("in.txt", "r", stdin);110     //freopen("out.txt", "w", stdout);111 #endif // OPEN_FILE112     int T;113     scanf("%d", &T);114     while(T--){115         scanf("%d%d%d", &n, &m, &t);116         scanf("%d%d%d", &s, &g, &h);117         int x, y, z;118         p.init(n);119         for(int i = 1; i <= m; i++){120             scanf("%d%d%d", &x, &y, &z);121             p.AddEdge(x, y, z);122             p.AddEdge(y, x, z);123         }124         p.dijstra(s);125         res.clear();126         for(int i = 1; i <= t; i++){127             scanf("%d", &x);128             for(int j = 0; j < road[x].size(); j++){129                 road[x][j].insert(x);130                 if(road[x][j].find(g) != road[x][j].end() && road[x][j].find(h) != road[x][j].end()){131                     res.push_back(x);132                     break;133                 }134             }135         }136         sort(res.begin(), res.end());137         int w = res.size();138         for(int i = 0; i < w; i++){139             printf("%d ", res[i]);140         }141         printf("\n");142     }143 }

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