字符串重排

#include <iostream>
#include <string>
#include <unordered_map>
using namespace std;
int main()
{
    string str;
    cin >> str;
    unordered_map<char, int> cnt;
    for(auto& c : str) cnt[c] ++;
    int ac = cnt['a'] - 1;
    int bc = cnt['b'];
    int cc = cnt['c'] / 3;
    int res = min(ac, bc);
    res = min(res, cc);
    cout << res << endl;
}

会合

7的倍数

中位数

#include <iostream>
#include <algorithm>
using namespace std;
const int N = 2010;
int a[N], ans[N], tem[N];
int sum;
int main()
{
    int n; cin >> n;
    for(int i = 1; i <= n; ++i)
        cin >> a[i];
    int lm;
    if(n & 1) lm = n;//n为奇数
    else lm = n - 1;//n为偶数
    //长度为1的区间和中位数就是本身
    for(int i = 1; i <= n; ++ i)
        sum += a[i];
    //枚举奇数区间长度
    for(int i = 3; i <= lm; i += 2)
    {
        //枚举区间起点
        for(int j = 1; j <= n - i + 1; ++ j)
        {
            int e = j + i - 1;//e为区间终点
            for(int k = 1; k <= n; ++ k)
                tem[k] = a[k];
            sort(tem + j, tem + e + 1);
            sum += tem[(j + e) / 2];
        }
    }
    printf("%d", sum);
    return 0;
}