2805 나무 자르기 (PS)

#include <stdio.h>
 
long long arr[1000001] = { 0 };
 
int main() {
    int n, m;
    scanf("%d %d", &n, &m);
    getchar();
 
    long long max = 0;
    for (int i = 1; i <= n; i++) {
        scanf("%lld", &arr[i]);
    }
 
    long long low = 0, high = 1000000000;
    while (low + 1 < high) {
        long long mid = (low + high) / 2;
        long long sum = 0;
//        printf("%lld %lld\n", low, high);
        for (int i = 1; i <= n; i++) {
            if(arr[i]>mid)
                sum += (arr[i] - mid);            
        }
        
        if (sum > m) {            
            low = mid;
        }
        else if (sum < m) {            
            high = mid;
        }
        else {
            printf("%lld", mid);
            return 0;
        }
        
    }
    printf("%lld", low);
}