题解 | #合唱队#

#include <iostream>
#include <vector>
#include <stack>
using namespace std;

int main() {
    int n;
    while (cin >> n) 
    {
        vector<int> heights;
        for (int i = 0; i < n; i++) {
            int num;
            cin >> num;
            heights.push_back(num);
        }
        int count = 0;
        vector<int> dp1(n,0);
        //左侧最长递增子序列长度
        for (int i = 0; i < n; i++) {
            dp1[i] = 1;  // 初始化为1
            for (int j = 0; j < i; j++)
                if (heights[j] < heights[i])
                    dp1[i] = max(dp1[i], dp1[j] + 1);
        }
        //右侧最长递增子序列
        vector<int> dp2(n,0);
        for (int i = n-1; i >=0 ; i--) {
            dp2[i] = 1;  // 初始化为1
            for (int j = n-1; j > i; j--)
                if (heights[j] < heights[i])
                    dp2[i] = max(dp2[i], dp2[j] + 1);
        }
        for (int i = 0; i <n; i++)
            count = max(count, dp1[i] + dp2[i] - 1);  // 减去重复计算的i位置
        cout << n- count << endl;
    }
    return 0;
}