C++14(g++5.4) 解法, 执行用时: 2ms, 内存消耗: 508K, 提交时间: 2020-08-14 15:15:00

#include<bits/stdc++.h>
using namespace std;
const int N = 56;
int n, m, tot = 1, a[N][N][2], f[N * N], ans;
char s[N][N];
bool v[N * N];
vector<int> e[N * N];

bool dfs(int x) {
	for (unsigned int i = 0; i < e[x].size(); i++) {
		int y = e[x][i];
		if (v[y]) continue;
		v[y] = 1;
		if (!f[y] || dfs(f[y])) {
			f[y] = x;
			return 1;
		}
	}
	return 0;
}

int main() {
	//freopen("in.txt", "r", stdin);
	cin >> n >> m;
	for (int i = 1; i <= n; i++) scanf("%s", s[i] + 1);
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m + 1; j++)//m + 1
			if (s[i][j] == '*') a[i][j][0] = tot;
			else ++tot;
	int t = tot;
	for (int j = 1; j <= m; j++)
		for (int i = 1; i <= n + 1; i++)
			if (s[i][j] == '*') a[i][j][1] = tot;
			else ++tot;
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++)
			if (s[i][j] == '*') {
				e[a[i][j][0]].push_back(a[i][j][1]);
				e[a[i][j][1]].push_back(a[i][j][0]);
			}

	for (int i = 1; i < t; i++) {
		memset(v, 0, sizeof(v));
		ans += dfs(i);
	}
	cout << ans << endl;
}

C++(clang++11) 解法, 执行用时: 5ms, 内存消耗: 476K, 提交时间: 2020-10-31 21:12:40

#include<bits/stdc++.h>
using namespace std;
const int N = 51;
int n, m, tot = 1, a[N][N][2], f[N * N], ans;
char s[N][N];
bool v[N * N];
vector<int> e[N * N];

bool dfs(int x) {
	for (unsigned int i = 0; i < e[x].size(); i++) {
		int y = e[x][i];
		if (v[y]) continue;
		v[y] = 1;
		if (!f[y] || dfs(f[y])) {
			f[y] = x;
			return 1;
		}
	}
	return 0;
}

int main()
{
	cin >> n >> m;
	for (int i = 1; i <= n; i++) scanf("%s", s[i] + 1);
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m + 1; j++)
			if (s[i][j] == '*') a[i][j][0] = tot;
			else ++tot;
	int t = tot;
	for (int j = 1; j <= m; j++)
		for (int i = 1; i <= n + 1; i++)
			if (s[i][j] == '*') a[i][j][1] = tot;
			else ++tot;
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++)
			if (s[i][j] == '*') {
				e[a[i][j][0]].push_back(a[i][j][1]);
				e[a[i][j][1]].push_back(a[i][j][0]);
			}

	for (int i = 1; i < t; i++) {
		memset(v, 0, sizeof(v));
		ans += dfs(i);
	}
	cout << ans << endl;
    return 0;
}