week16- C1. Zekken Easy, Author Solution

#include <bits/stdc++.h>
#define PB push_back
#define F first
#define S second
typedef long long LL;
using namespace std;
const int MOD = 1e9+7;
const int SIZE = 2001;
vector<pair<int,int> > pp;
int dp[SIZE];
int main(){
    int n,d;
    scanf("%d%d",&n,&d);
    pp.PB(make_pair(0,0));
    for(int i=0;i<n;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        pp.PB(make_pair(y,x));
    }
    sort(pp.begin(),pp.end());
    memset(dp,-1,sizeof(dp));
    dp[0]=0;
    int an=0;
    for(int i=1;i<=n;i++){
        for(int j=0;j<i;j++){
            if(dp[j]==-1)continue;
            if(abs(pp[i].S-pp[j].S)<=d*(LL)(pp[i].F-pp[j].F)){
                dp[i]=max(dp[i],dp[j]+1);
            }
        }
        an=max(an,dp[i]);
    }
    printf("%d\n",an);
    return 0;
}