最长上升子序列 O(nlogn)

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

const int maxn = 1e5 + 10;
#define inf 0x3f3f3f3f
int N, ans;
int dp[maxn], a[maxn], num[maxn];

int main() {
    scanf("%d", &N);
    for(int i = 0; i < N; i ++)
        scanf("%d", &a[i]);

    fill(dp, dp + N, inf);
    ans = -1;

    for(int i = 0; i < N; i ++) {
        int pos = lower_bound(dp, dp + N, a[i]) - dp;
        num[i] = pos + 1;
        ans = max(ans , num[i]);
        dp[pos] = a[i];
    }

    printf("%d\n", ans);

    return 0;
}