最长上升子序列-冗余优化版-二分

重点
1. q中存的是当前所有长度的序列的结尾最小的值
2. q一定是单调递增的，反证法
3. dp思想->贪心

#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 100010;
int a[N];
int q[N];

int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) cin >> a[i];
    int len = 0;
    q[0] = -2e9;
    for (int i = 0; i < n; i++) {
        int l = 0, r = len;
        while (l < r) {
            int mid = (l + r + 1) >> 1;
            if (q[mid] < a[i]) l = mid;
            else r = mid - 1;
        }
        len = max(len, l + 1);
        q[l + 1] = a[i];
    }
    cout << len << endl;
    return 0;
}