HDU 1051 Wooden Sticks

题目地址：​​点击打开链接​​

思路：贪心+动归

AC代码：

#include<stdio.h>
#include<algorithm>
using namespace std;
struct wood
{
  int head;
  int tail;
  int flag;
}a[5010];
int cmp(struct wood x,struct wood y)
{
  if(x.head != y.head)
    return x.head < y.head;
  else
    return x.tail < y.tail;
}
int main()
{
  int t,n,i,j,ans,end;
  scanf("%d",&t);
  while(t--)
  {
    ans = 0;
    scanf("%d",&n);
    for(i=0; i<n; i++)
    {
      scanf("%d%d",&a[i].head,&a[i].tail);
      a[i].flag = 1;
    }
    sort(a,a+n,cmp);
    for(i=0; i<n; i++)
    {
      if(a[i].flag)
      {
        ans++;
        a[i].flag = 0;
        end = a[i].tail;
        for(j=i+1; j<n; j++)
        {
          if(a[j].flag  && a[j].tail >= end)
          {
            a[j].flag = 0;
            end = a[j].tail;
          }
        }
      }
    }
    printf("%d\n",ans);
  }
  return 0;
}