///
/// You fell for it, fool!
/// Thunder Cross Split Attack!
///
#include <bits/stdc++.h>
#define Loop(x,l,r) for(ll x = ll(l); x < ll(r); ++x)
typedef long long ll;
typedef std::pair<int,int> pii;
using namespace std;
const int N = 3009;
int ch, cv;
char a[N][N];
int n, m;
vector<int> A[N*N/3];
int mp[2][N][N];
int mch[N*N/3];
pii par[N*N/3];
bitset<N*N/3> vis;
bool gdh(int i, int j){return 0 <= i && i < n && 0 <= j && j+3 <= m && a[i][j] == 'R' && a[i][j+1] == 'G' && a[i][j+2] == 'W';}
bool gdv(int i, int j){return 0 <= i && i+2 <= n && 0 <= j && j < m && a[i][j] == 'R' && a[i+1][j] == 'G' && a[i+2][j] == 'W';}
bool bfs(int s)
{
par[s] = {-1, -1};
vector<int> q;
q.push_back(s); vis[s] = 1;
for(int i = 0; i < q.size(); ++i)
{
int v = q[i];
for(int u : A[v])
{
if(mch[u] == 0){
while(v != -1){
mch[u] = v;
u = par[v].S;
v = par[v].F;
}
for(int z : q) vis[z] = 0;
return 1;
}
if(vis[mch[u]]) continue;
q.push_back(mch[u]);
vis[mch[u]] = 1;
par[mch[u]] = {v, u};
}
}
return 0;
}
int main()
{
ios::sync_with_stdio(false); cin.tie(0);
cin >> n >> m;
Loop(i,0,n) cin >> a[i];
Loop(i,0,n) Loop(j,0,m) {
if(gdh(i,j)) mp[0][i][j] = ++ch;
if(gdv(i,j)) mp[1][i][j] = ++cv;
}
Loop(i,0,n) Loop(j,0,m) {
if(gdh(i,j)){
if(gdv(i,j)) A[mp[0][i][j]].push_back(mp[1][i][j]);
if(gdv(i-1,j+1)) A[mp[0][i][j]].push_back(mp[1][i-1][j+1]);
if(gdv(i-2,j+2)) A[mp[0][i][j]].push_back(mp[1][i-2][j+2]);
}
}
int ans = ch + cv;
Loop(v,1,ch+1)
{
ans -= bfs(v);
}
cout << ans << '\n';
}
Compilation message
dango_maker.cpp: In function 'bool bfs(int)':
dango_maker.cpp:30:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
30 | for(int i = 0; i < q.size(); ++i)
| ~~^~~~~~~~~~
dango_maker.cpp:38:17: error: 'pii' {aka 'struct std::pair<int, int>'} has no member named 'S'
38 | u = par[v].S;
| ^
dango_maker.cpp:39:17: error: 'pii' {aka 'struct std::pair<int, int>'} has no member named 'F'
39 | v = par[v].F;
| ^
