2217 로프

#include <stdio.h>
 
int arr[100001] = { 0 };
 
void qSort(int left, int right) {
    int l = left + 1, r = right, num=arr[left];
 
    do {
        while (arr[l] <= num && l < right) l++;
        while (num <= arr[r] && left < r) r--;
 
        if (l < r) {
            int temp = arr[r];
            arr[r] = arr[l];    
            arr[l] = temp;
        }
    } while (l < r);
 
    int temp = arr[r];
    arr[r] = arr[left];
    arr[left] = temp;
 
    if(left<r-1) qSort(left, r - 1);
    if(r+1<right) qSort(r + 1, right);
}
 
int main() {
    int n, rst = 0;
    scanf("%d", &n);
    
    for (int i = 0; i < n; i++)
        scanf("%d", &arr[i]);
 
    qSort(0, n - 1);
 
    for (int i = 0; i < n; i++) {
        if (rst < arr[i] * (n - i))
            rst = arr[i] * (n - i);
    }
 
    printf("%d", rst);
}