最大字段和

贪心

#include<cstdio>#include<iostream>#include<cstring>#include<vector>#include<algorithm>using namespace std;struct st{    int s,t;}a[1999999];int ans,m,n,k,r,f[1999][1509],w[1999],v[1999],t[1999],minn=1e9+7;bool cmp(const st &a,const st &b){    return a.t<b.t||a.t==b.t&&a.s<b.s;}int main(){    scanf("%d%",&n);    for(int i=1;i<=n;i++)    {        scanf("%d%d",&a[i].s,&a[i].t);    }     sort(a+1,a+n+1,cmp);    int x=a[1].t,ans=1;    for(int i=2;i<=n;i++){        if(a[i].s>=x) ans++,x=a[i].t;    }    printf("%d",ans);}