hdu2819二分图匹配

时间:2022-11-30 18:06:55
Given an N*N matrix with each entry equal to 0 or 1. You can swap any two rows or any two columns. Can you find a way to make all the diagonal entries equal to 1?

InputThere are several test cases in the input. The first line of each test case is an integer N (1 <= N <= 100). Then N lines follow, each contains N numbers (0 or 1), separating by space, indicating the N*N matrix.OutputFor each test case, the first line contain the number of swaps M. Then M lines follow, whose format is “R a b” or “C a b”, indicating swapping the row a and row b, or swapping the column a and column b. (1 <= a, b <= N). Any correct answer will be accepted, but M should be more than 1000.

If it is impossible to make all the diagonal entries equal to 1, output only one one containing “-1”. 
Sample Input

2
0 1
1 0
2
1 0
1 0

Sample Output

1
R 1 2
-1
题意:给一个只有0 1的矩阵,是否能通过交换两行或者两列使对角线全为1
题解:二分图匹配x和y,输出方法是关键,两遍循环取对应的xy不相同的进行交换记录交换的行或者列(由矩阵知识可知行和列交换一种就行了)
刚开始因为but M should be more than 1000. 这句话我非要作死输出1000个,话说题目能不能不要瞎写啊!!!
#include<map>
#include<set>
#include<cmath>
#include<queue>
#include<stack>
#include<vector>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#define pi acos(-1)
#define ll long long
#define mod 1000000007 using namespace std; const int N=+,maxn=+,inf=0x3f3f3f3f; int color[N],n;
bool used[N],ok[N][N]; bool match(int x)
{
for(int i=;i<=n;i++)
{
if(ok[x][i]&&!used[i])
{
used[i]=;
if(color[i]==||match(color[i]))
{
color[i]=x;
return ;
}
}
}
return ;
}
int solve()
{
int ans=;
memset(color,,sizeof color);
for(int i=;i<=n;i++)
{
memset(used,,sizeof used);
ans+=match(i);
}
return ans;
}
int main()
{
ios::sync_with_stdio(false);
cin.tie();
while(cin>>n){
for(int i=;i<=n;i++)
for(int j=;j<=n;j++)
cin>>ok[i][j];
if(solve()!=n)cout<<-<<endl;
else
{
// for(int i=1;i<=n;i++)cout<<color[i]<<endl;
memset(used,,sizeof used);
queue<pair<int,int> >q;
for(int i=;i<=n;i++)
{
if(i==color[i])continue;
for(int j=i+;j<=n;j++)
{
if(j==color[j])continue;
if(i==color[j])
{
q.push(make_pair(i,j));
swap(color[i],color[j]);
}
}
}
cout<<q.size()<<endl;
while(!q.empty()){
cout<<"C "<<q.front().first<<" "<<q.front().second<<endl;
q.pop();
}
}
}
return ;
}