2015’12杭电校赛1004 Happy Value （最大生成树）

题解

最大生成树，用kruskal算法把排序函数符合改一下就是最大生成树了

代码

#include <cstdio>
#include <queue>
#include <cstring>
#include <iostream>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <set>
#include <ctime>
#include <cmath>
#include <cctype>
using namespace std;
#define MAX 100000
#define LL long long

struct Edge
{
int from,to,dist;
Edge(){}
Edge(int u,int v,int d):from(u),to(v),dist(d){}
}edge[110*110];

int f[110];

bool cmp(Edge a,Edge b)
{
return a.dist>b.dist;
}

int Find(int x){
if(f[x] == x) return x;
return f[x] = Find(f[x]);
}

int main()
{
int n;
while(scanf("%d",&n)!=EOF)
{
int num = 0;
for(int i=1;i<=n;i++) f[i] = i;
for(int i=1;i<=n;i++)
{
for(int j=1;j<=n;j++)
{
int w;
scanf("%d",&w);
edge[num++] = Edge(i,j,w);
}
}

sort(edge,edge+num,cmp);
int ans = 0;
for(int i=0;i<num;i++)
{
int u = edge[i].from,v = edge[i].to,w = edge[i].dist;
u = Find(f[u]);
v = Find(f[v]);
if(u==v)
continue;
f[u] = v;
ans += w;
}
printf("%d\n",ans);
}
}

题目

Happy Value

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 1455 Accepted Submission(s): 429

Problem Description

In an apartment, there are N residents. The Internet Service Provider (ISP) wants to connect these residents with N – 1 cables.

However, the friendships of the residents are different. There is a “Happy Value” indicating the degrees of a pair of residents. The higher “Happy Value” is, the friendlier a pair of residents is. So the ISP wants to choose a connecting plan to make the highest sum of “Happy Values”.

Input

There are multiple test cases. Please process to end of file.

For each case, the first line contains only one integer N (2<=N<=100), indicating the number of the residents.

Then N lines follow. Each line contains N integers. Each integer Hij(0<=Hij<=10000) in ith row and jth column indicates that ith resident have a “Happy Value” Hij with jth resident. And Hij(i!=j) is equal to Hji. Hij(i=j) is always 0.

Output

For each case, please output the answer in one line.

Sample Input

2

0 1

1 0

3

0 1 5

1 0 3

5 3 0

Sample Output

1

8