蛤蛤蛤（树状数组 | 二分）

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裸Lis

n² 解法谁都会

下面是 nlogn 的解法

树状数组

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cstring>

using namespace std;

const int MAXN = 100001;
int n, cnt, ans;
int a[MAXN], b[MAXN], c[MAXN];

inline int query(int x)
{
    int ans = 0;
    for(; x; x -= x & -x) ans = max(ans, c[x]);
    return ans;
}

inline void update(int x, int d)
{
    for(; x <= cnt; x += x & -x) c[x] = max(c[x], d);
}

int main()
{
    int i, j, x, y;
    scanf("%d", &n);
    for(i = 1; i <= n; i++) scanf("%d", &a[i]), b[i] = a[i];
    sort(b + 1, b + n + 1);
    cnt = unique(b + 1, b + n + 1) - (b + 1);
    for(i = 1; i <= n; i++)
    {
        x = lower_bound(b + 1, b + cnt + 1, a[i]) - b;
        y = query(x - 1) + 1;
        update(x, y);
        ans = max(ans, y);
    }
    printf("%d", n - ans);
    return 0;
}

二分（原先的我真是naive）

#include <cstdio>
#include <iostream>

using namespace std;

int n, m, a[100011], b[100011], s, len, mid;

int main()
{
    int i, j, k, x, y;
    cin >> n;
    for(i = 1; i <= n; i++)    cin >> a[i];
    b[1] = a[1];
    len = 1;
    for(i = 2; i <= n; i++)
    {
        x = 1;
        y = len;
        while(x <= y)
        {
            mid = (x + y) / 2;
            if(a[i] > b[mid]) x = mid + 1;
            else y = mid - 1;
        }
        b[x] = a[i];
        if(x > len) len = x;
    }
    cout << n - len;
    return 0;
}