【CodeForces 615E】Hexagons

找规律。

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cmath>
#define N 10005
#define ll long long
using namespace std;
ll n,t,x,y;
ll fx[10]={1,-1,-2,-1,1,2,1};
ll fy[10]={2,2,0,-2,-2,0,2};
int main(){
    cin>>n;
    if(n==0){
        puts("0 0");
        return 0;
    }
    t=sqrt(n/3);
    while(t*(t+1)*3>=n)t--;
    x=t*2;
    y=0;
    n-=t*(t+1)*3;
    if(n){
        x+=fx[0];
        y+=fy[0];
        n--;
    }
    ll s=min(t,n);
    x+=fx[1]*s;
    y+=fy[1]*s;
    n-=s;
    
    ll d=2;
    ll dx=0,dy=0;
    t++;
    while(n>=t){
        dx+=fx[d];
        dy+=fy[d];
        d++;
        printf("%lld ",d);
        n-=t;
    }
    x+=fx[d]*n;
    y+=fy[d]*n;
    cout<<x+dx*t<<" "<<y+dy*t<<endl;
}