poj3522求一棵生成树使最大的边和最小的边差值最小

/*题目：给出一张图，求一棵生成树使得最大边权和最小边权差值最小*//*思路：对边权排序，依次枚举最小边，再与后边组成生成树，直到满足题意。若不连通，输出-1,反之，输出差值*/#include <cstdio>#include <algorithm>#define N 100using namespace std;const int inf = 0x3f3f3f3f;typedef struct note {int u; int v; int w;}edge;int n, m;edge e[N*N];int f[N];int cmp(edge a, edge b){return a.w < b.w;}void init(){for (int i = 1; i <= n; i++)f[i] = i;}int find(int x){return x == f[x] ? x : f[x] = find(f[x]);}int merge(int x, int y){int t1, t2;t1 = find(x); t2 = find(y);if (t1 != t2) { f[t2] = f[t1]; return 1; }return 0;}int main(){while (scanf("%d%d", &n, &m) != EOF && (n || m)){int ans = inf;for (int i = 0; i < m; i++)scanf("%d%d%d", &e[i].u, &e[i].v, &e[i].w);sort(e, e + m, cmp);for (int i = 0; i < m; i++){int cnt = 0;init();for (int j = i; j < m; j++){if (merge(e[j].u, e[j].v))cnt++;if (cnt == n - 1){ans = min(ans, e[j].w - e[i].w);break;}}}if (ans == inf)ans = -1;printf("%d\n", ans);}return 0;}