poj 2485 Highways

来源：互联网发布：linux ansi 编辑：程序博客网时间：2024/06/18 00:18

用kruskal（）算法处理》》。

 1 #include<stdio.h> 2 #include<stdlib.h> 3 #define MAXN 300000 4  5 int T, n, h, u[MAXN], v[MAXN], w[MAXN], p[510], r[MAXN]; 6  7 int cmp(const void *_p, const void *_q) 8 { 9     int *p = (int *)_p;10     int *q = (int *)_q;11     return w[*p] - w[*q];12 }13 14 int find(int x){return p[x] == x ? x : p[x] = find(p[x]);}15 16 void kruskal()17 {18     int ans = 0;19     for(int i = 0; i < n; i ++) p[i] = i;20     for(int i = 0; i < h; i ++) r[i] = i;21     qsort(r,h,sizeof(r[0]),cmp);22     for(int i = 0; i < h; i ++)23     {24         int e = r[i], x = find(u[e]), y = find(v[e]);25         if(x != y){ans = w[e]; p[x] = y;}26     }27     printf("%d\n",ans);28 }29 30 int main()31 {32     while(~scanf("%d",&T))33     {34         while(T--)35         {36             scanf("%d",&n);37             h = 0;38             for(int i = 0; i < n; i ++)39             {40                 for(int j = 0; j < n; j ++)41                 {42                     int a;43                     scanf("%d",&a);44                     if(i == j) continue;45                     u[h] = i, v[h] = j, w[h++] = a;46                 }47             }48             kruskal();49         }50     }    51 }

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