nyoj891找点

#include<stdio.h>

#include<algorithm>

using namespace std;

struct ch{

int s,e;

}a[101];

bool cmp(struct ch a,struct ch b)

{

if(a.e != b.e) return a.e > b.e;

else return a.s > b.s;

}

int main()

{

int n,i;

while(scanf("%d",&n) != EOF)

{

for(i = 0;i < n;i++)

{

scanf("%d %d",&a[i].s,&a[i].e);

}

sort(a,a+n,cmp);

int l = 0,r = 101,point = 1;

for(i = 0;i < n;i++)

{

if(r >= a[i].e && l <= a[i].e)

{

r = a[i].e;

if(l < a[i].s) l = a[i].s;

}

else

{

point++;

r = a[i].e;

l = a[i].s;

}

}

printf("%d\n",point);

}

return 0;

}

思路：将输入的n个数组先有区间从大到小排序然后有区间若是相等就左区间从大到小排序。然后，每次区间比较的时候去交集然后在进行比较。