| Time Limit: 2 second(s) | Memory Limit: 32 MB |
Given n points (1 dimensional) and q segments, you have to find the number of points that lie in each of the segments. A point pi will lie in a segment A B if A ≤ pi ≤ B.
For example if the points are 1, 4, 6, 8, 10. And the segment is 0 to 5. Then there are 2 points that lie in the segment.
Input starts with an integer T (≤ 5), denoting the number of test cases.
Each case starts with a line containing two integers n (1 ≤ n ≤ 105) and q (1 ≤ q ≤ 50000). The next line contains n space separated integers denoting the points in ascending order. All the integers are distinct and each of them range in [0, 108].
Each of the next q lines contains two integers Ak Bk (0 ≤ Ak ≤ Bk ≤ 108) denoting a segment.
For each case, print the case number in a single line. Then for each segment, print the number of points that lie in that segment.
Sample Input |
Output for Sample Input |
|
1 5 3 1 4 6 8 10 0 5 6 10 7 100000 |
Case 1: 2 3 2 |
Dataset is huge, use faster I/O methods.
这个不是二分答案的那种题了,是比较正常的那种集合区间中的那种元素查找的二分题目了。题意很简单,给n个有序的数,这些数分布在一个坐标轴上。给q次查找,询问在区间[x, y](这里的符号和代码的保持一致)中有多少个数据。
解法就是自己写一个二分函数upper_bound和lower_bound,然后直接计算区间即可。
/****
*@author Shen
*@title LightOj 1088
*/
#include <iostream>
#include <cstdio>
#include <cmath>
#include <algorithm>
using namespace std;
const int maxN = 100005;
int a[maxN];
int t, tt;
int n, q, x, y;
int Bsearch_lower_bound(int x)
{
int l = 0, r = n - 1, mid = 0;
while (l <= r)
{
mid = (l + r) >> 1;
if (a[mid] < x) l = mid + 1;
else r = mid - 1;
}
return l;
}
int Bsearch_upper_bound(int x)
{
int l = 0, r = n - 1, mid = 0;
while (l <= r)
{
mid = (l + r) >> 1;
if (a[mid] <= x) l = mid + 1;
else r = mid - 1;
}
return l;
}
void solve()
{
scanf("%d%d", &n, &q);
printf("Case %d:\n", ++tt);
for (int i = 0; i < n; i++)
scanf("%d", &a[i]);
for (int i = 0; i < q; i++)
{
scanf("%d%d", &x, &y);
int l = Bsearch_lower_bound(x);
int r = Bsearch_upper_bound(y);
printf("%d\n", r - l);
}
}
int main()
{
scanf("%d", &t);
while (t--) solve();
return 0;
}LightOJ 1088 Points in Segments 二分查找,布布扣,bubuko.com
LightOJ 1088 Points in Segments 二分查找
原文地址:http://blog.csdn.net/polossk/article/details/26403695