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| #include <bits/stdc++.h>
#define MAX_N 101
#define ll long long
#define pll pair<ll, ll>
#define all(a) begin(a), end(a)
using namespace std;
ll n, m, cc, pc;
ll match[MAX_N], seen[MAX_N], a[MAX_N];
ll id[MAX_N][MAX_N];
ll dis[MAX_N][MAX_N];
string pkl[MAX_N];
void bfs(ll cy, ll cx, ll ck) {
queue<pll> q;
bool vis[MAX_N][MAX_N];
memset(vis, false, sizeof(vis));
q.push({cy,cx});
ll dy[4]{-1,0,1,0}, dx[4]{0,1,0,-1}, d = 1;
vis[cy][cx] = true;
while(!q.empty()) {
ll sz = q.size();
while(sz--) {
auto [y, x] = q.front(); q.pop();
for(ll i = 0; i < 4; i++) {
ll ny = y + dy[i], nx = x + dx[i];
if(0 <= ny and ny < n and 0 <= nx and nx < m and !vis[ny][nx] and pkl[ny][nx] != 'X') {
vis[ny][nx] = true;
q.push({ny,nx});
dis[ck][id[ny][nx]] = d;
}
}
}
d++;
}
}
void init() {
for(ll i = 0; i < n; i++)
for(ll j = 0; j < m; j++)
if(pkl[i][j] == 'P') id[i][j] = ++pc;
for(ll i = 0; i < n; i++)
for(ll j = 0; j < m; j++)
if(pkl[i][j] == 'C')
bfs(i,j,++cc);
}
ll dfs(ll u, ll s, ll t) {
for(ll i = 1; i <= pc; i++) {
if(seen[i] == s or dis[u][i] > t) continue;
seen[i] = s;
if(match[i] == -1 or dfs(match[i], s, t)) {
match[i] = u;
return 1;
}
}
return 0;
}
ll biMatch(ll t) {
ll res = 0;
for(ll i = 1; i <= cc; i++) {
if(dfs(i,i,t))
res++;
}
return res;
}
ll solve() {
if(!cc) return 0;
if(cc > pc) return -1;
for(ll i = 1; i <= cc; i++)
for(ll j = 1; j <= pc; j++)
if(!dis[i][j]) dis[i][j] = INT_MAX;
ll l = 1, r = INT_MAX, res = INT_MAX;
while(l <= r) {
ll m = l + (r - l) / 2;
memset(match, -1, sizeof(match));
memset(seen, -1, sizeof(seen));
ll ma = biMatch(m);
if(ma == cc) {
res = m;
r = m - 1;
}
else l = m + 1;
}
return res == INT_MAX ? -1 : res;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin>>n>>m;
for(ll i = 0; i < n; i++) cin>>pkl[i];
init();
cout<<solve();
return 0;
}
|
