【动态规划】bzoj1664 [Usaco2006 Open]County Fair Events 参加节日庆祝

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;
}