HDU2819-Swap-二分图匹配

把矩阵上的1建成边，把边建成点

然后跑一个二分图匹配，就找到了主对角线的元素，之后排个序就可以了

/*--------------------------------------------------------------------------------------*/

#include <algorithm>
#include <iostream>
#include <cstring>
#include <ctype.h>
#include <cstdlib>
#include <cstdio>
#include <vector>
#include <string>
#include <queue>
#include <stack>
#include <cmath>
#include <set>
#include <map>

//debug function for a N*M array
#define debug_map(N,M,G) printf("
");for(int i=0;i<(N);i++)
{for(int j=0;j<(M);j++){
printf("%d",G[i][j]);}printf("
");}
//debug function for int,float,double,etc.
#define debug_var(X) cout<<#X"="<<X<<endl;
#define LL long long
const int INF = 0x3f3f3f3f;
const LL LLINF = 0x3f3f3f3f3f3f3f3f;
/*--------------------------------------------------------------------------------------*/
using namespace std;

int N,M,T;
const int maxn = 210;
const int maxm = 10010;

struct Edge{
    int to,next;
}edge[maxm];
int head[maxn],tot;
void init()
{
    tot = 0;
    memset(head,-1,sizeof head);
}
void add_edge(int u,int v)
{
    edge[tot].to = v;edge[tot].next = head[u];
    head[u] = tot++;
}

int linker[maxn];
bool used[maxn];
int uN;

bool dfs(int u)
{
    for(int i=head[u];~i;i =edge[i].next)
    {
        int v = edge[i].to;
        if(!used[v])
        {
            used[v] = true;
            if(linker[v] == -1 || dfs(linker[v]))
            {
                linker[v] = u;
                return true;
            }
        }
    }
    return false;
}

int hungary()
{
    int res = 0;
    memset(linker,-1,sizeof linker);
    for(int u=1;u<=uN;u++)
    {
        memset(used,false,sizeof used);
        if(dfs(u)) res++;
    }
    return res/2;
}
vector <pair<int,int> > op;
int save[maxn];

bool ok()
{
    for(int i=1;i<=N;i++) if(save[i] != i) return false;
    return true;
}

int main()
{
    while(~scanf("%d",&N))
    {
        uN = 2*N;
        init();
        for(int i=1;i<=N;i++)
        {
            for(int j=1,tmp;j<=N;j++)
            {
                scanf("%d",&tmp);
                if(tmp == 1)
                {
                    add_edge(i,j+N);
                    add_edge(j+N,i);
                }
            }
        }
        int match = hungary();
        if(match < N)
        {
            printf("-1
");
        }
        else
        {
            for(int u=1;u<=N;u++)
            {
                int v = linker[u] - N;
                //printf("[%d,%d]
",u,v);
                save[u] = v;
            }
            op.clear();
            while(!ok())
            {
                for(int i=1;i<=N;i++)
                {
                    if(save[i] != i)
                    {
                        op.push_back(make_pair(i,save[i]));
                        swap(save[i],save[save[i]]);
                    }
                }
            }
            printf("%d
",op.size());
            for(int i=0;i<op.size();i++)
            {
                printf("R %d %d
",op[i].first,op[i].second);
            }
        }
    }
}