poj 1679 http://poj.org/problem?id=1679

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<ctype.h>
#include<stdlib.h>
#define INF 0x3f3f3f3f
#define max(a, b)(a > b ? a : b)
#define min(a, b)(a < b ? a : b)
#define N 110

int maps[N][N], Max[N][N];//maps[i][j]线段线段ij的花费，Max记录树外最大的线段的花费
int dist[N], f[N], n;//f[i]  i的父节点即将点i连入树的起点，dist[i]将i连入树需要的花费
bool vis[N], use[N][N];//vis[i]标记点i是否在树种，use[i][j]标记线段ij是否在树中

void Init()//初始化
{
    memset(vis, false, sizeof(vis));
    memset(use, false, sizeof(use));
    memset(dist, 0, sizeof(dist));
    memset(f, 0, sizeof(f));
    int i, j;
    for(i = 0 ; i < N ; i++)
    {
        for(j = 0 ; j < N ; j++)
        {
            if(i == j)
                maps[i][j] = 0;
            else
                maps[i][j] = INF;
        }
    }
}

int prim(int s)//求最小生成树
{
    int index, Min, i, j, ans = 0;
    for(i = 1 ; i <= n ; i++)
    {
        dist[i] = maps[s][i];
        f[i] = s;
    }
    vis[s] = true;
    for(i = 1 ; i < n ; i++)
    {
        Min = INF;
        for(j = 1 ; j <= n ; j++)
        {
            if(!vis[j] && dist[j] < Min)
            {
                Min = dist[j];
                index = j;
            }
        }
        vis[index] = true;
        ans += Min;
        use[f[index]][index] = use[index][f[index]] = true;
        for(j = 1 ; j <= n ; j++)
        {
            if(vis[j] && index != j)
                Max[index][j] = Max[j][index] = max(Max[f[index]][j], maps[f[index]][index]);
            if(!vis[j] && dist[j] > maps[index][j])
            {
                dist[j] = maps[index][j];
                f[j] = index;
            }
        }
    }
    return ans;
}

int SMST(int num)//求次小生成树
{
    int i, j, Min = INF;
    for(i = 1 ; i < n ; i++)
    {
        for(j = i + 1 ; j <= n ; j++)
        {
            if(!use[i][j] && maps[i][j] != INF)
                Min = min(Min, num + maps[i][j] - Max[i][j]);
        }
    }
    return Min;
}

int main()
{
    int t, m, x, y, w, num1, num2;
    scanf("%d", &t);
    while(t--)
    {
        Init();
        scanf("%d%d", &n, &m);
        while(m--)
        {
            scanf("%d%d%d", &x, &y, &w);
            maps[x][y] = maps[y][x] = w;
        }
        num1 = prim(1);
        num2 = SMST(num1);
        if(num1 == num2)//最小生成树与次小生成树相等，则最小生成树不唯一
            printf("Not Unique!\n");
        else
            printf("%d\n", num1);
    }
    return 0;
}