codeforces600B

一个长度为n的数列a[]，一个长度为m的数列b[]，在a中查找小于等于b[i]的值

二分求解：

#include <stdio.h>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<math.h>
using namespace std;
const int maxn = 1e6 + 10;
typedef long long ll;
int n, m;
ll a[maxn];
ll b[maxn];
int dfs(int l, int r, int j)
{
	if (b[j] >= a[n])return n;
	if (b[j] < a[1])return 0;
	int mid = (l + r) / 2;
	if (a[mid - 1] <= b[j] && a[mid] > b[j])
		return mid - 1;
	if (a[mid + 1] > b[j] && a[mid] <= b[j])
		return mid;
	if (a[mid] > b[j]) {
		r = mid;
		dfs(l, r, j);
	}
	else if (a[mid] <= b[j]) {
		l = mid;
		dfs(l, r, j);
	}
}
int main()
{
	cin >> n >> m;
	for (int i = 1; i <= n; ++i)
		cin >> a[i];
	for (int j = 1; j <= m; ++j)
		cin >> b[j];
	sort(a + 1, a + 1 + n);
	for (int j = 1; j <= m; ++j) {
		cout << dfs(1, n, j)<<' ';
	}
	cout << endl;
	return 0;
}