每日一题：

标题

class Solution {
public:
    bool isCovered(vector<vector<int>>& f, int left, int right) {
        vector<int> d(52, 0);
        for (auto &t : f)
        {
            d[t[0]] ++ ;
            d[t[1] + 1] -- ; 
        }
        
        int sum = 0;
        for (int i = 1; i <= 50; i ++ )
        {
            sum += d[i];
            if (i >= left && i <= right && sum <= 0)
                return false;
        }
        return true;
    }
};

砖块

#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>

using namespace std;

int main()
{
    int T;
    scanf("%d", &T);
    while (T -- )
    {
        int n;
        string a, b;
        cin >> n >> a;
        b = a;
        bool flag = false;
        int p = 0;
        vector<int> res;
        for (int i = 0; i < n - 1; i ++ )
        {
            if (b[i] == 'W')
            {
                b[i] = 'B';
                b[i + 1] = b[i + 1] == 'W'?'B':'W';
                res.push_back(i + 1);
            }
        }
        if (b[n - 1] == b[n - 2])
        {
            cout << res.size() << endl;
            if (res.size())
            {
                for (auto &t:res)
                    cout << t << ' ';
                cout << endl;
            }
            continue;
        }
        res.clear();
        b = a;
        for (int i = 0; i < n - 1; i ++ )
        {
            if (b[i] == 'B')
            {
                b[i] = 'W';
                b[i + 1] = b[i + 1] == 'W'?'B':'W';
                res.push_back(i + 1);
            }
        }
        if (b[n - 1] == b[n - 2])
        {
            cout << res.size() << endl;
            if (res.size())
            {
                for (auto &t:res)
                    cout << t << ' ';
                cout << endl;
            }
            continue;
        }
        cout << -1 << endl;
    }
    return 0;
}