A - Flag of Berland

思路:

Code:

#include <bits/stdc++.h>
using namespace std;

const int N = 105;  

int n, m;
vector<string> s(N), ss(N);  

bool check(int n, int m) {
    if (n % 3) return false;
    int divide = n / 3;
    if (s[divide] == s[0] || s[divide * 2] == s[0] || s[divide] == s[divide * 2]) return false;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (s[i][j] != s[i / divide * divide][0]) return false; 
        }
    }
    return true;
}

int main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
    cin >> n >> m;
    for (int i = 0; i < n; i++) {
        cin >> s[i];
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            ss[j].push_back(s[i][j]); 
        }
    }
    if (check(n, m)) {
        cout << "YES\n";
        return 0;
    }
    swap(n, m);
    s.clear(); // 清空字符串数组
    s.resize(n); // 重新设置大小
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            s[i].push_back(ss[i][j]); // 使用push_back函数向vector中添加元素
        }
    }
    if (check(n, m)) {
        cout << "YES\n";
    } else {
        cout << "NO\n";
    }
    return 0;
}

B - Darker and Darker

Code:

/* 
遍历所有的#统计最大即可简单bfs就行
 */
#include <bits/stdc++.h>
    
using namespace std; 
typedef pair<int, int> PII;
const int N = 1e3 + 5;

char arr[N][N]; 
int n, m, ans;
int dir[4][2] = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};

bool isVaild(int x, int y) {
    return x >= 1 && x <= n && y >= 1 && y <= m && arr[x][y] == '.';
}

queue<array<int, 3>> q;

void bfs() {
    while (!q.empty()) {
        auto [x, y, cnt] = q.front(); q.pop();
        for (int i = 0; i < 4; ++i) {
            int dx = x + dir[i][0];
            int dy = y + dir[i][1];
            if (isVaild(dx, dy)) { 
                arr[dx][dy] = '#';
                q.push({dx, dy, cnt + 1});
                ans = max(ans, cnt + 1);
            }
        }
    }
    cout << ans << '\n';
    return ;
}

int main() {
    ios::sync_with_stdio(false); cin.tie(0);cout.tie(0);
    cout << fixed << setprecision(12);
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j<= m; j++) {
            cin >> arr[i][j];
            if (arr[i][j] == '#') {
                q.push({i, j, 0}); 
            }
        }
    }
    bfs();
    return 0;
}