Codeforces 600B Queries about less or equal elements(二分、upper_bound()的应用)

Queries about less or equal elements

You are given two arrays of integers a and b. For each element of the second array bj you should find the number of elements in array a that are less than or equal to the value bj.
Input
The first line contains two integers n, m (1 ≤ n, m ≤ 2·105) — the sizes of arrays a and b.
The second line contains n integers — the elements of array a ( - 109 ≤ ai ≤ 109).
The third line contains m integers — the elements of array b ( - 109 ≤ bj ≤ 109).
Output
Print m integers, separated by spaces: the j-th of which is equal to the number of such elements in array a that are less than or equal to the value bj.
Example
Input
5 4
1 3 5 7 9
6 4 2 8
Output
3 2 1 4
Input
5 5
1 2 1 2 5
3 1 4 1 5
Output
4 2 4 2 5
思路：排序后二分查找即可，用upper_bound更快。upper_bound（）返回的是被查序列中第一个大于查找值的指针，也就是返回指向被查值>查找值的最小指针

#include <iostream>
#include <cstdio>
#include <algorithm>

using namespace std;

const int maxn = 2e5 + 10;

int main()
{
    int n, m;
    int a[maxn], b[maxn];
    scanf("%d%d", &n, &m);
    for(int i = 0; i < n; i++)
    {
        scanf("%d", &a[i]);
    }
    sort(a, a+n);
    for(int j = 0; j < m; j++)
    {
        scanf("%d", &b[j]);
    }
    for(int j = 0; j < m; j++)
    {
        int pos = upper_bound(a, a+n, b[j]) - a;
        if(j==m-1)
            printf("%d\n", pos);
        else
            printf("%d ", pos);
    }
    return 0;
}