将区间按左端点排序。
f(i)=max{f(j)+1}(p[j].x+p[j].y<=p[i].x && j<i)
#include<cstdio>
#include<algorithm>
using namespace std;
int n,f[10001];
struct Point{int x,y;}p[10001];
bool operator < (const Point &a,const Point &b){return a.x<b.x;}
int main()
{
scanf("%d",&n);
for(int i=1;i<=n;++i) scanf("%d%d",&p[i].x,&p[i].y);
sort(p+1,p+1+n);
for(int i=1;i<=n;++i) f[i]=1;
for(int i=1;i<=n;++i)
for(int j=1;j<i;++j)
if(p[j].x+p[j].y<=p[i].x)
f[i]=max(f[j]+1,f[i]);
printf("%d\n",*max_element(f+1,f+n+1));
return 0;
}