模拟赛#1补题 CodeForces 580B（排序+二分）

【题目链接】：click here~~

B. Kefa and Company

time limit per test
2 seconds

memory limit per test
256 megabytes

input
standard input

output
standard output

Kefa wants to celebrate his first big salary by going to restaurant. However, he needs company.

Kefa has n friends, each friend will agree to go to the restaurant if Kefa asks. Each friend is characterized by the amount of money
he has and the friendship factor in respect to Kefa. The parrot doesn't want any friend to feel poor compared to somebody else in the company (Kefa doesn't count). A friend feels poor if in the company there is someone who has at least d units
of money more than he does. Also, Kefa wants the total friendship factor of the members of the company to be maximum. Help him invite an optimal company!

Input

The first line of the input contains two space-separated integers, n and d (1 ≤ n ≤ 105, 

)
— the number of Kefa's friends and the minimum difference between the amount of money in order to feel poor, respectively.

Next n lines contain the descriptions of Kefa's friends, the (i + 1)-th
line contains the description of the i-th friend of type mi, si(0 ≤ mi, si ≤ 109)
— the amount of money and the friendship factor, respectively.

Output

Print the maximum total friendship factir that can be reached.

Sample test(s)

input

4 5
75 5
0 100
150 20
75 1

output

100

input

5 1000 7
11 32
99 10
46 8
87 54

output

111

Note

In the first sample test the most profitable strategy is to form a company from only the second friend. At all other variants the total degree of friendship will be worse.

In the second sample test we can take all the friends.

【题目大意】：给你一个集合，集合中的每个元素有两个属性，moner(钱数),factor(友情值) 让你求个子集合，使得集合中的最大money的差不超过d的情况下，factor的和的最大值 

【思路】；

我们考虑先按money递增排序，枚举第一个人，然后枚举其他人，依次判断即可，注意此题两个坑点~~

代码：

/*
* Problem: CodeForces 580B
* Running time: 421MS
* Complier: G++
* Author: herongwei
* Create Time: 21:00 2015/10/13 星期二
*/
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
using namespace std;
typedef long long LL;
const int maxn=1e5+10;
struct node
{
int mon,fac;
bool operator <(const node& t)const{
return mon<t.mon;
}
}st[maxn];
LL sum[maxn]={0};
int main()
{
//freopen("1.txt","r",stdin);
int n,d;cin>>n>>d;
for(int i=1; i<=n; ++i) cin>>st[i].mon>>st[i].fac;
sort(st+1,st+n+1);
for(int i=1; i<=n; ++i) sum[i]=sum[i-1]+st[i].fac;
int l=1,r=1;
LL ans=0;
for(; l<=n; ++l)
{
while(r<=n&&st[r].mon-st[l].mon<d) r++;///写成<=就会WA在第八组数据，没用long long会WA在第九组数据
ans=max(ans,sum[r-1]-sum[l-1]);
}
printf("%lld\n",ans);
return 0;
}