信息学奥赛一本通 1240：查找最接近的元素

题目链接：http://ybt.ssoier.cn:8088/problem_show.php?pid=1240

#include <iostream>
#include <cstdio>

using namespace std;

const int N = 100010;

int a[N];

int main()
{
    int n;
    scanf("%d", &n);
    
    for (int i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
    }
    
    int m;
    scanf("%d", &m);
    
    while (m--)
    {
        int x;
        scanf("%d", &x);
        
        if (x <= a[0])
        {
            printf("%d\n", a[0]);
        }
        else if (x >= a[n - 1])
        {
            printf("%d\n", a[n - 1]);
        }
        else
        {
            // 查找大于等于x的数中最小的
            int l = 0, r = n - 1;
            while (l < r)
            {
                int mid = l + r >> 1;
                if (a[mid] >= x) r = mid;
                else l = mid + 1;
            }
            
            if (x - a[l - 1] <= a[l] - x)
            {
                printf("%d\n", a[l - 1]);
            }
            else
            {
                printf("%d\n", a[l]);
            }
        }
    }
    
    return 0;
}