洛谷P2062 分队问题(dp)

// luogu-judger-enable-o2
// luogu-judger-enable-o2
#include<cstdio>
#include<algorithm>
#define LL long long 
using namespace std;
const int MAXN = 1e6 + 10;
inline int read() {
    char c = getchar(); int x = 0, f = 1;
    while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}
    while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();
    return x * f;
}
int N;
int a[MAXN], f[MAXN];
int main() {
    N = read();
    for(int i = 1; i <= N; i++) a[i] = read();
    sort(a + 1, a + N + 1);
    int res = N, ans = 0;
    for(int i = 1; i <= N; i++) {
        if(a[i] <= i) f[i] = 1;
        if((i - a[i] >= 1))
            f[i] = max(f[i], f[i - a[i]] + 1);
        ans = max(ans, f[i]);
    }
    printf("%d", ans);
    return 0;
}
/*
4
2 3 3 3
*/