CF：706B. Interesting drink （二分查找）

题意：不同奶茶店里同样的奶茶价格不同，问在当天Yuki持有的零钱能在几家店购买

思路：对价格数组排序，先优先判断是否会比较最大值和最小值，然后二分查找

#include<bits/stdc++.h>
using namespace std;
int main() {
    int n, q, m, a[100005];
    cin >> n; for (int i = 1; i <= n; ++i)cin >> a[i];
    sort(a + 1, a + 1 + n);//可以改用qsort，效率更高点
    cin >> q;
    while (q--) {
        cin >> m;
        //比较最大最小值
        if (m < a[1])cout << 0 << endl;
        else if (m >= a[n])cout << n << endl;
        else {
            int left = 1, right = n;
            int mid, ans;
            while (left <= right) {
                mid = (left + right) / 2;
                if (a[mid] <= m) {
                    ans = mid;
                    left = mid + 1;
                }
                else right = mid - 1;
            }
            cout << ans << endl;
        }
    }
}