uva 1396 Slim Span

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Kruskal 算法

注意数组不要越界，尽量开大点，其他没什么注意，这种算法的水题

#include <cstdio>#include <cmath>#include <algorithm>#include <iostream>//#define T///////////////using namespace std;const int M = 220;int f[M];struct edge{    int x;    int y;    int u;};edge e[10000];void s_union(int a, int b);bool cmp(edge a,edge b);int f_find(int a);int counter;int ans;int n,m;void inital(){    for(int i = 0; i <= 200; i ++)        f[i] = i;    counter = 1;}bool cmp(edge a,edge b){    return a.u < b.u;}int f_find(int a){    if(a != f[a])        f[a] = f_find(f[a]);    return f[a];}void s_union(int a, int b){    if(a > b)        f[b] = a;    else        f[a] = b;}int main(){int l,i,j,r;    while(~scanf("%d %d",&n,&m) && (n||m))    {        ans = 0x3f3f3f3f;        for( i = 0; i < m; i ++)            scanf("%d %d %d",&e[i].x,&e[i].y,&e[i].u);            sort(e,e+m,cmp);            for(j = 0; j < m; j++)            {                inital();                for( i = j; i < m; i++)                {                    l = f_find(e[i].x);                    r = f_find(e[i].y);                    if(l != r)                    {                        s_union(l,r);                        counter++;                       // printf("counter ----- %d\n",counter);                    }                    if(counter == n)                    {                        ans = min(ans,e[i].u - e[j].u);                        break;                    }                }             }             if(ans == 0x3f3f3f3f)                printf("%d\n",-1);             else            printf("%d\n",ans);    }    return 0;}

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