【HDOJ】1688 Sightseeing

Dijkstra求解次短路径，使用cnt和dis数组记录最小、次小的个数和长度。重写更新操作。

 /* 1688 */
 #include <iostream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <vector>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <cstring>
 #include <climits>
 #include <cctype>
 using namespace std;

 #define MAXN 1005
 #define INF  0x3f3f3f3f

 typedef struct Edge_t {
     int v, w;
     Edge_t() {}
     Edge_t(int u, int ww) {
         v = u; w = ww;
     }
 } Edge_t;

 vector<Edge_t> vc[MAXN];
 bool visit[MAXN][];
 int dis[MAXN][];
 int cnt[MAXN][];
 int n, m;

 void init() {
     int i;

     for (i=; i<=n; ++i)
         vc[i].clear();
     memset(cnt, , sizeof(cnt));
 }

 int dijkstra(int s, int f) {
     int i, j, k, tmp, r;
     int u, v, w, mmin;
     int ret = ;
     Edge_t e;

     memset(visit, false, sizeof(visit));
     memset(dis, 0x3f, sizeof(dis));
     dis[s][] = ;
     cnt[s][] = ;

     for (r=; r<n*; ++r) {
         mmin = INF;
         u = -;
         for (j=; j<=n; ++j) {
             if (!visit[j][] && dis[j][]<mmin) {
                 mmin = dis[j][];
                 u = j;
                 k = ;
             } else if  (!visit[j][] && dis[j][]<mmin) {
                 mmin = dis[j][];
                 u = j;
                 k = ;
             }
         }
         if (u == -)
             break;
         visit[u][k] = true;
         for (i=; i<vc[u].size(); ++i) {
             e = vc[u][i];
             v = e.v;
             w = e.w;
             tmp = w + dis[u][k];
             if (tmp < dis[v][]) {
                 dis[v][] = dis[v][];
                 cnt[v][] = cnt[v][];
                 dis[v][] = tmp;
                 cnt[v][] = cnt[u][k];
             } else if (tmp == dis[v][]) {
                 cnt[v][] += cnt[u][k];
             } else if (tmp < dis[v][]) {
                 dis[v][] = tmp;
                 cnt[v][] = cnt[u][k];
             } else if (tmp == dis[v][]) {
                 cnt[v][] += cnt[u][k];
             }
         }
     }

     ret += cnt[f][];
     if (dis[f][]+ == dis[f][])
         ret += cnt[f][];
     return ret;
 }

 int main() {
     int t;
     int i, j, k;
     Edge_t e;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     scanf("%d", &t);
     while (t--) {
         scanf("%d %d", &n, &m);
         init();
         while (m--) {
             scanf("%d %d %d", &i, &e.v, &e.w);
             vc[i].push_back(e);
         }
         scanf("%d %d", &i, &j);
         k = dijkstra(i, j);
         printf("%d\n", k);
     }

     return ;
 }