【日常训练】Volleyball（CodeForces-96D）

题意与分析

这题也是傻逼题，可是我当时打比赛的时候板子出问题了- -|||，怎么调也调不过。

不过思路是很清晰的：先做n次dijkstra然后重新建图，建完了以后根据新的单向图再跑一次dijkstra。

代码

 #include <bits/stdc++.h>

 #define ZERO(x) memset(x, 0, sizeof(x))
 using namespace std;
 using ll=long long;

 struct Edge { int v, nxt; ll c; };
 Edge w[];
 vector<int>    que;
 ll dist[], a[], b[];
 int    e[][], ww[];
 bool vis[];
 int    N, M, x, y, W = ;

 void ShortestPath(int s)
 {
     memset(dist, , sizeof(dist)); dist[s] = ;
     ZERO(vis); vis[s]=true;
     que.clear();
     que.push_back(s);
     for (int fi = ; fi < que.size(); ++ fi)
     {
         int    u = que[fi];
         for (int i = ww[u]; i; i = w[i].nxt)
         {
             int    v = w[i].v;
             if (dist[v] <= dist[u] + w[i].c) continue;
             dist[v] = dist[u] + w[i].c;
             if (vis[v]) continue;
             vis[v] = true;
             que.push_back(v);
         }
         vis[u] = false;
     }

     e[s][] = ;
     for (int i = ; i <= N; ++ i)
         if (i != s && dist[i] <= a[s]) e[s][++ e[s][]] = i;
 }

 int    main()
 {
     cin >> N >> M;
     cin >> x >> y;
     for (int i = , u, v; i <= M; ++ i)
     {
         ll    c;
         cin >> u >> v >> c;
         w[++ W].v = v; w[W].c = c; w[W].nxt = ww[u]; ww[u] = W;
         w[++ W].v = u; w[W].c = c; w[W].nxt = ww[v]; ww[v] = W;
     }
     for (int i = ; i <= N; ++ i) cin >> a[i] >> b[i];
     for (int i = ; i <= N; ++ i) ShortestPath(i);

     memset(dist, , sizeof(dist)); dist[x] = ;
     ZERO(vis); vis[x]=true;
     que.clear();
     que.push_back(x);
     for (int fi = ; fi < que.size(); ++ fi)
     {
         int    u = que[fi];
         for (int i = ; i <= e[u][]; ++ i)
         {
             int    v = e[u][i];
             if (dist[v] <= dist[u] + b[u]) continue;
             dist[v] = dist[u] + b[u];
             if (vis[v]) continue;
             vis[v] = ;
             que.push_back(v);
         }
         vis[u] = ;
     }

     if (dist[y] > (1ll << )) dist[y] = -;
     cout << dist[y] << endl;

     return ;
 }

点我看时雨色图