Shortest way Codeforces Round #103 (Div. 2) D. Missile Silos

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1 /*2 Shortest way: Not only scan the edges, but also scan the points; There are two cases, one is just at the midpoint, that is, from the u,v, then the last/23 there is a different from the u,v, both of the distance is L4 The template was wrong and it was a long time: (5 */6#include <cstdio>7#include <algorithm>8#include <cstring>9#include <cmath>Ten#include <vector> One#include <queue> A using namespacestd; -  - Const intMAXN = 1e5 +Ten; the Const intINF =0x3f3f3f3f; - intD[MAXN]; - intCNT[MAXN]; - BOOLVIS[MAXN]; +vector<pair<int,int> >G[MAXN]; - intN, M, S, l, ans, ans2; +  A voidSPFA (void) { atmemset (Vis,false,sizeof(Vis)); -memset (d, INF,sizeof(d)); D[s] =0;  -queue<int>Q; Q.push (s); -      while(!Q.empty ()) { -         intU =Q.front (); Q.pop (); -Vis[u] =false; in          for(intI=0; I<g[u].size (); ++i) { -             intv = g[u][i].first;intW =G[u][i].second; to             if(D[v] > D[u] +W) { +D[V] = D[u] +W; -                 if(!Vis[v]) { theVIS[V] =true; Q.push (v); *                 } $             }    Panax Notoginseng         } -     } the } +  A intMainvoid)  {//codeforces Round #103 (Div. 2) D. Missile Silos the     //freopen ("spfa.in", "R", stdin); +      -      while(SCANF ("%d%d%d", &n, &m, &s) = =3)   { $          for(intI=1; i<=m; ++i) { $             intU, V, W; scanf ("%d%d%d", &u, &v, &W); - G[u].push_back (Make_pair (V, W)); G[v].push_back (Make_pair (U, W)); -         } thescanf ("%d", &l); SPFA (); -         WuyiAns = Ans2 =0; the          for(intI=1; i<=n; ++i) { -              for(intj=0; J<g[i].size (); ++j) { Wu                 intU = i, V = g[i][j].first, w =G[i][j].second; -                 if(D[u] < L && L-d[u] <W) { About                     if(W-(L-d[u]) + d[v] > L) ans++; $                     Else if(D[u] + d[v] + W = =2* L) ans2++; -                 } -             } -             if(D[i] = = L) ans++; A         } +printf ("%d\n", ans + ans2/2); the     } -  $     return 0; the}

Shortest way Codeforces Round #103 (Div. 2) D. Missile Silos