HDU2819-Swap-二分图匹配

Posted 2020-08-05 Helica

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

  1 /*--------------------------------------------------------------------------------------*/
  2 
  3 #include <algorithm>
  4 #include <iostream>
  5 #include <cstring>
  6 #include <ctype.h>
  7 #include <cstdlib>
  8 #include <cstdio>
  9 #include <vector>
 10 #include <string>
 11 #include <queue>
 12 #include <stack>
 13 #include <cmath>
 14 #include <set>
 15 #include <map>
 16 
 17 //debug function for a N*M array
 18 #define debug_map(N,M,G) printf("\n");for(int i=0;i<(N);i++) 19 {for(int j=0;j<(M);j++){ 20 printf("%d",G[i][j]);}printf("\n");}
 21 //debug function for int,float,double,etc.
 22 #define debug_var(X) cout<<#X"="<<X<<endl;
 23 #define LL long long
 24 const int INF = 0x3f3f3f3f;
 25 const LL LLINF = 0x3f3f3f3f3f3f3f3f;
 26 /*--------------------------------------------------------------------------------------*/
 27 using namespace std;
 28 
 29 int N,M,T;
 30 const int maxn = 210;
 31 const int maxm = 10010;
 32 
 33 struct Edge{
 34     int to,next;
 35 }edge[maxm];
 36 int head[maxn],tot;
 37 void init()
 38 {
 39     tot = 0;
 40     memset(head,-1,sizeof head);
 41 }
 42 void add_edge(int u,int v)
 43 {
 44     edge[tot].to = v;edge[tot].next = head[u];
 45     head[u] = tot++;
 46 }
 47 
 48 int linker[maxn];
 49 bool used[maxn];
 50 int uN;
 51 
 52 bool dfs(int u)
 53 {
 54     for(int i=head[u];~i;i =edge[i].next)
 55     {
 56         int v = edge[i].to;
 57         if(!used[v])
 58         {
 59             used[v] = true;
 60             if(linker[v] == -1 || dfs(linker[v]))
 61             {
 62                 linker[v] = u;
 63                 return true;
 64             }
 65         }
 66     }
 67     return false;
 68 }
 69 
 70 int hungary()
 71 {
 72     int res = 0;
 73     memset(linker,-1,sizeof linker);
 74     for(int u=1;u<=uN;u++)
 75     {
 76         memset(used,false,sizeof used);
 77         if(dfs(u)) res++;
 78     }
 79     return res/2;
 80 }
 81 vector <pair<int,int> > op;
 82 int save[maxn];
 83 
 84 bool ok()
 85 {
 86     for(int i=1;i<=N;i++) if(save[i] != i) return false;
 87     return true;
 88 }
 89 
 90 int main()
 91 {
 92     while(~scanf("%d",&N))
 93     {
 94         uN = 2*N;
 95         init();
 96         for(int i=1;i<=N;i++)
 97         {
 98             for(int j=1,tmp;j<=N;j++)
 99             {
100                 scanf("%d",&tmp);
101                 if(tmp == 1)
102                 {
103                     add_edge(i,j+N);
104                     add_edge(j+N,i);
105                 }
106             }
107         }
108         int match = hungary();
109         if(match < N)
110         {
111             printf("-1\n");
112         }
113         else
114         {
115             for(int u=1;u<=N;u++)
116             {
117                 int v = linker[u] - N;
118                 //printf("[%d,%d]\n",u,v);
119                 save[u] = v;
120             }
121             op.clear();
122             while(!ok())
123             {
124                 for(int i=1;i<=N;i++)
125                 {
126                     if(save[i] != i)
127                     {
128                         op.push_back(make_pair(i,save[i]));
129                         swap(save[i],save[save[i]]);
130                     }
131                 }
132             }
133             printf("%d\n",op.size());
134             for(int i=0;i<op.size();i++)
135             {
136                 printf("R %d %d\n",op[i].first,op[i].second);
137             }
138         }
139     }
140 }