[SDOI2004]打鼹鼠

 1 #include<cstdio>
 2 #include<queue>
 3 #include<iostream>
 4 #include<cstring>
 5 #define int long long 
 6 inline int abs(int x){if(x<0) return -x;return x;}
 7 using namespace std;
 8 inline int read(){
 9     int ans=0,f=1;char chr=getchar();
10     while(!isdigit(chr)){if(chr=='-') f=-1;chr=getchar();}
11     while(isdigit(chr)){ans=(ans<<3)+(ans<<1)+chr-48;chr=getchar();}
12     return ans*f;
13 }int n,m,x[10005],y[10005],z[10005],f[10005],ans;
14 signed main(){
15     n=read(),m=read();
16     for(int i=1;i<=m;i++)    z[i]=read(),x[i]=read(),y[i]=read(),f[i]=1;
17     for(int i=1;i<=m;i++){
18         for(int j=1;j<i;j++)
19             if(z[i]-z[j]>=abs(x[i]-x[j])+abs(y[i]-y[j]))
20                 f[i]=max(f[j]+1,f[i]);
21         ans=max(ans,f[i]);
22     }cout<<ans;
23     return 0;
24 }