【洛谷 P4086】【SACO17DEC】My Cow Ate My Homework

Description

　　你有长度为n的成绩序列，最终成绩为去掉一个最低的成绩后剩下的平均值（多个最低只去掉一个），现在你可以删除前k个（1<=k<=n-2），按升序输出所有可以使你最终成绩最高的K的值。

Solution

　　考虑线段树， 维护区间和与区间最小值，最后枚举k，计算出平均值，更新答案

Code

 

#include 
const int N = 1e5 + 10;
using namespace std;
int n, summ, m, cnt;
int a[N], ans[N];
struct emmm {
    int l, r;
    int sum, minn;
    #define l(x) tr[x].l
    #define r(x) tr[x].r
    #define sum(x) tr[x].sum
    #define minn(x) tr[x].minn
} tr[N << 2];
void build(int p, int l, int r) {
    l(p) = l;
    r(p) = r;
    if (l == r) {
        sum(p) = a[l];
        minn(p) = a[l];
        return ;
    }
    int mid = (l + r) >> 1;
    build(p << 1, l, mid);
    build(p << 1 | 1, mid + 1, r);
    sum(p) = sum(p << 1) + sum(p << 1 | 1);
    minn(p) = min(minn(p << 1), minn(p << 1 | 1));
}
void query(int p, int l, int r) {
    if (l <= l(p) && r >= r(p)) {
        summ += sum(p);
        m = min(m, minn(p));
        return ;
    }
    int mid = (l(p) + r(p)) >> 1;
    if (l <= mid) query(p << 1, l, r);
    if (r > mid) query(p << 1 | 1, l, r);
    return ;
}
int main() {
    ios::sync_with_stdio(0);
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    build(1, 1, n);
    double t = 0;
    for (int i = 1; i <= n - 2; i++) {
        summ = 0;
        m = 0x3f3f3f;
        query(1, i + 1, n);
        double s = (double)(summ - m) / (double)(n - i - 1);
        if (t == s) 
            ans[++cnt] = i;
        else if (s > t) {
            cnt = 0;
            ans[++cnt] = i;
            t = s;
        }
    }
    for (int i = 1; i <= cnt; i++) 
        cout << ans[i] << endl;
    return 0;
}

 

 

 

 

转载于:https://www.cnblogs.com/-sheldon/p/11428259.html