题目分析:
- 按照 r从小到大排序,如果与前一个区间的不重叠,就贪
Code:
#include <bits/stdc++.h>
using namespace std;
#define maxn 1000010
int n;
struct node {
int l,r;
}e[maxn];
inline int read_() {
int x=0,f=1;
char c=getchar();
while(c<'0'||c>'9') {
if(c=='-') f=-1;
c=getchar();
}
while(c>='0'&&c<='9') {
x=(x<<1)+(x<<3)+c-'0';
c=getchar();
}
return x*f;
}
inline bool cmp_(node aa,node bb) {
return aa.r < bb.r;
}
void readda_() {
n=read_();
for(int i=1;i<=n;++i) {
e[i].l=read_();e[i].r=read_();
}
sort(e+1,e+n+1,cmp_);
int ans=0,last=-1;
for(int i=1;i<=n;++i) {
if(e[i].l>=last) {
++ans;
last=e[i].r;
}
}
printf("%d",ans);
}
int main() {
freopen("a.txt","r",stdin);
readda_();
return 0;
}