Problem Description
There is an undirected graph G with n vertices and m edges. Every time, you can select several edges and delete them. The edges selected must meet the following condition: let G′ be graph induced from these edges, then every connected component of G′ has at most one cycle. What is the minimum number of deletion needed in order to delete all the edges.
Input
There are multiple test cases. The first line of input contains an integer T indicating the number of test cases. For each test case:
The first line contains two integers n and m (1≤n≤2000,0≤m≤2000) -- the number of vertices and the number of edges.
For the next m lines, each line contains two integers ui and vi, which means there is an undirected edge between ui and vi (1≤ui,vi≤n,ui≠vi).
The sum of values of n in all test cases doesn't exceed 2⋅104. The sum of values of m in all test cases doesn't exceed 2⋅104.
Output
For each test case, output the minimum number of deletion needed.
Sample Input
3
4 2
1 2
1 3
4 5
1 2
1 3
1 4
2 3
2 4
4 4
1 2
2 3
3 4
4 1
Sample Output
1
2
1
https://www.cnblogs.com/qscqesze/p/5246222.html
#include
#include
#include
#define MAXN 1000
int map[MAXN][MAXN];
int n;
void Prim()
{
int i, j, minV, sum;
int dis[n], pre[n];
bool vist[n] = {0};
vist[0] = 1;
for (i = 0; i < n; i++)
{
dis[i] = map[0][i];
pre[i] = 0;
}
sum = 0;
for (i = 1; i < n; i++)
{
minV = -1;
for (j = 0; j < n; j++)
if (!vist[j] && (minV < 0 || dis[j] < dis[minV]))
minV = j;
vist[minV] = 1;
sum += dis[minV];
for (j = 0; j < n; j++)
if (!vist[j] && dis[j] > map[minV][j])
{
dis[j] = map[minV][j];
pre[j] = minV;
}
}
printf("最小生成树的权为 = %d\n", sum);
for (i = 0; i < n; i++)
printf("边 %d - %d\n", i, pre[i]);
}
int main()
{
int i, j;
printf("请输入结点数n:\n");
scanf("%d", &n);
printf("请输入邻接矩阵:\n");
for (i = 0; i < n; i++)
for (j = 0; j < n; j++)
scanf("%d", &map[i][j]);
prim();
return 0;
}
//用prim写的，输入是邻接矩阵