【HDOJ】2363 Cycling

二分+Dijkstra。

 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <queue>
 using namespace std;

 #define MAXN 105
 #define INF  1000001

 int n, m;
 int map[MAXN][MAXN], al[MAXN], bk[MAXN], path[MAXN];
 bool visit[MAXN];
 int low, high;
 int ans, dif;

 int dijkstra() {
     int i, j, v, min;

     if (al[]<low || al[]>high)
         return INF;

     memset(visit, false, sizeof(visit));
     visit[] = true;
     for (i=; i<=n; ++i) {
         if (al[i]>=low && al[i]<=high)
             path[i] = map[][i];
         else
             path[i] = INF;
     }

     for (i=; i<n; ++i) {
         min = INF;
         for (j=; j<=n; ++j) {
             if (!visit[j] && path[j]<min) {
                 v = j;
                 min = path[j];
             }
         }
         if (min == INF)
             break;
         visit[v] = true;
         for (j=; j<=n; ++j) {
             if (!visit[j] && map[v][j]+min<path[j] && al[j]>=low && al[j]<=high)
                 path[j] = map[v][j] + min;
         }
     }
     return path[n];
 }

 int main() {
     int t, min, l, r, max, mid;
     int i, j, k, tmp;

     scanf("%d", &t);
     while (t--) {
         scanf("%d %d", &n, &m);
         min = dif = ;
         ans = INF;
         max = ;
         for (i=; i<=n; ++i) {
             scanf("%d", &al[i]);
             if (al[i] < min) min = al[i];
             if (al[i] > max) max = al[i];
             bk[i] = al[i];
         }
         for (i=; i<=n; ++i) {
             map[i][i] = ;
             for (j=i+; j<=n; ++j)
                 map[i][j] = map[j][i] = INF;
         }
         while (m--) {
             scanf("%d %d %d", &i, &j, &k);
             if (map[i][j] > k)
                 map[i][j] = map[j][i] = k;
         }
         sort(bk+, bk++n);
         l = ; r = max-min+;
         while (l < r) {
             mid = (l + r)>>;
             bool flag = false;
             for (i=; i<=n; ++i) {
                 low = bk[i];
                 high = bk[i] + mid;
                 tmp = dijkstra();
                 if (tmp != INF) {
                     flag = true;
                     break;
                 }
             }
             if ( flag ) {
                 if (mid < dif) {
                     dif = mid;
                     ans = tmp;
                 } else if (mid==dif && ans > tmp) {
                     ans = tmp;
                 }
                 r = mid;
             } else {
                 l = mid + ;
             }
         }
         printf("%d %d\n", dif, ans);
     }

     return ;
 }