雅礼2017国庆1-1

题解懒得写了...题目虽然不难，但是std的写法是最方便的，于是我就学了一遍。。。

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#define N 200005
using namespace std;
struct p{int x,y;}a[N];
bool cmp(p a,p b){return a.x<b.x;}
int n,ans=0;
int main()
{
    freopen("clique.in","r",stdin);
    freopen("clique.out","w",stdout);
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        int x,w;
        scanf("%d%d",&x,&w);
        a[i].x=x-w; a[i].y=x+w;
    }
    sort(a+1,a+n+1,cmp);
    int k=0;
    for(int i=1;i<=n;i++)
    {
        while(k && a[k].y>a[i].y)k--;
        a[++k]=a[i];
    }
    n=k;
    for(int i=1,e=-2000000005;i<=n;i++)
        if(a[i].x>=e){e=a[i].y;ans++;}
    printf("%d",ans);
    fclose(stdin);fclose(stdout);
    //system("pause");
    return 0;
}