Codeforces 1345 D

题目：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<map>
#include<queue>
#include<vector>
#include<string>
#include<fstream>

using namespace std;
typedef long long ll;
const int N = 2e3 + 105;
const int M = 1e6 + 5;
const int mod = 998244353;
const double Pi = acos(- 1.0);
const int INF = 0x3f3f3f3f;
const int G = 3, Gi = 332748118;
//

char mp[N][N];
int n, m;
bool visr[N], visc[N], visr2[N], visc2[N];
int root[N * N];

int Find(int x){
    return x == root[x] ? x : root[x] = Find(root[x]);
}

void Union(int x, int y){
    int tx = Find(x);
    int ty = Find(y);
    if(tx != ty){
        root[ty] = tx;
    }
}

int val(int x,int y){
    return (x - 1) * m + y;
}

void solve()
{
    for(int i = 1; i <= n * m; ++ i) root[i] = i;
    for(int i = 1; i <= n; ++ i){
        for(int j = 1; j <= m; ++ j){
            if(mp[i][j] == '#'){
                if(j < m &&mp[i][j + 1] == '#') Union(val(i,j), val(i,j + 1));
                if(i < n && mp[i + 1][j] == '#') Union(val(i,j), val(i + 1, j));
            }
        }
    }
    int res = 0;
    for(int i = 1; i <= n; ++ i){
        for(int j = 1; j <= m; ++ j){
            if(mp[i][j] == '#' && Find(val(i,j)) == val(i,j)){
                res ++;
            }
        }
    }
    printf("%d
",res);
}

int main()
{
    scanf("%d%d",&n,&m);
   int B = 0, W = 0, flag = 0;
   for(int i = 1; i <= n; ++ i){
       B = 0, W = 0;
       scanf("%s",mp[i]+1);
       for(int j = 1; j <= m; ++ j){
           if(mp[i][j] == '.') {
               W = 1;
               if(B) W = 2;
           }
           else if(mp[i][j] == '#'){
               B = 1;
               if(W == 2) flag = 1;
               visr[i] = 1;
               visc[j] = 1;
           }
       }
   }
   if(flag){
       //cout<<"1"<<endl;
       printf("-1
");
       return 0;
   }
   B = 0, W = 0, flag = 0;
   for(int j = 1; j <= m; ++ j){
       B = 0, W = 0;
       for(int i = 1; i <= n; ++ i){
           if(mp[i][j] == '.'){
               W = 1;
               if(B) W = 2;
           }
           else if(mp[i][j] == '#'){
               B = 1;
               if(W == 2) flag = 1;
           }
       }
   }
   if(flag){
       //cout<<"2"<<endl;
       printf("-1
");
       return 0;
   }

   for(int i = 1; i <= n; ++ i)
       for(int j = 1; j <= m; ++ j){
           if(!visr[i] && !visc[j]) {
               //cout<<i<<" "<<j<<endl;
               visr2[i] = 1;
               visc2[j] = 1;
           }
       }
       
   for(int i = 1; i <= n; ++ i) 
       if(!visr[i] && !visr2[i]) {
           flag = 1;
       }
   for(int i = 1; i <= m; ++ i)
       if(!visc[i] && !visc2[i]) {
           flag = 1;
       }
   if(flag){
       //cout<<"3"<<endl;
       printf("-1
");
       return 0;
   }
   solve();
   return 0;
}
/*
3 7
......#
.......
#......
*/