Codeforces 830C Bamboo Partition (看题解)

Bamboo Partition

列公式， 整除分块， 想不到， 好菜啊。

#include<bits/stdc++.h>
#define LL long long
#define fi first
#define se second
#define mk make_pair
#define PLL pair<LL, LL>
#define PLI pair<LL, int>
#define PII pair<int, int>
#define SZ(x) ((int)x.size())
#define ull unsigned long long

using namespace std;

const int N =  + ;
const int inf = 0x3f3f3f3f;
const LL INF = 0x3f3f3f3f3f3f3f3f;
const int mod = 1e9 + ;
const double eps = 1e-;
const double PI = acos(-);

LL n, k, a[N], b[], tar, tot;

int main() {
    scanf("%lld%lld", &n, &k);
    for(int i = ; i <= n; i++) {
        scanf("%lld", &a[i]);
        tar += a[i];
        a[i]--;
    }
    tar += k;
    for(int i = ; i <= n; i++) {
        for(int j = , k; j < a[i]; j = k + ) {
            k = a[i] / (a[i] / j);
            b[tot++] = j;
        }
        b[tot++] = a[i] + ;
    }
    sort(b, b + tot);
    tot = unique(b, b + tot) - b;
    for(int i = tot - ; i >= ; i--) {
        LL d = b[i], val = ;
        for(int i = ; i <= n; i++)
            val += d * (a[i] / d);
        if(n * d + val <= tar) {
            val = ;
            for(int i = ; i <= n; i++) val += a[i] / d;
            printf("%lld\n", tar / (val + n));
            return ;
        }
    }
    return ;
}

/*
*/