poj 1870 Bee Breeding

思路：首先要建立坐标，具体作法见：http://www.cnblogs.com/xin-hua/p/3237096.html

然后将得到2坐标之差x,y；如果x,y同号，则相加，否则去最大.(要取绝对值的)

代码如下：

#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<iomanip>
#include<cmath>
#include<cstring>
#include<vector>
#define ll __int64
#define pi acos(-1.0)
#define MAX 50000
using namespace std;
struct dir
{
    int x,y;
    dir(){}
    dir(int a,int b){
        x=a;
        y=b;
    }
    dir operator+(dir A){
        return dir(A.x+x,A.y+y);
    }
}an[6];
dir solve(int n)
{
    int k,m,i,j;
    dir p;
    k=((sqrt(12.0*n-3.0)-3.0)/6.0);
    if(3*k*(k+1)+1!=n) k++;
    p.x=k;p.y=0;
    m=0;
    if(k>0) m=6*k-((3*k*(k+1)+1)-n);
    i=0;
    while(m){
        for(j=0;j<k;j++){
            p=p+an[i];
            m--;
            if(m==0)
                break;
        }
        i++;
    }
    return p;
}
int main(){
    int n,x,y,ans,m;
    an[0]=dir(-1,1);an[1]=dir(-1,0);an[2]=dir(0,-1);
    an[3]=dir(1,-1);an[4]=dir(1,0);an[5]=dir(0,1);
    while(cin>>n>>m){
        if(m==0&&n==0) break;
        dir aa=solve(n);
        dir bb=solve(m);
        x=aa.x-bb.x;
        y=aa.y-bb.y;
        if((x<0&&y<0)||(x>0&&y>0))
            ans=abs(x+y);
        else ans=max(abs(x),abs(y));
        printf("The distance between cells %d and %d is %d.
",n,m,ans);
    }
    return 0;
}