poj 2886 Who Gets the Most Candies?

#include<stdio.h>
#include<string.h>
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
const int MN= 500100;
int sum[MN<<2];
int next[MN];
char nam[MN][20];

int a[37]={1,2,4,6,12,24,36,48,60,120,180,240,360,720,840,1260,1680,2520,5040,7560,10080,15120,20160,25200,27720,45360,50400,
           55440,83160,110880,166320,221760,277200,332640,498960,500001};
int b[37]={1,2,3,4,6,8,9,10,12,16,18,20,24,30,32,36,40,48,60,64,72,80,84,90,96,100,108,120,128,144,160,168,180,192,200,1314521};

void PushUP(int rt)
{
    sum[rt]=sum[rt<<1]+sum[rt<<1|1];
}

void build(int l,int r,int rt)
{
    if(l==r)
    {
        sum[rt]=1;
        return ;
    }
    int m=(l+r)>>1;
    build(lson);
    build(rson);
    PushUP(rt);
}

int query(int k,int l,int r,int rt)
{
    if(l==r)
    {
        sum[rt]--;
        return l;
    }
    int m=(l+r)>>1;
    int ret;
    if(k<=sum[rt<<1]) ret=query(k,lson);
    else
    {
        k-=sum[rt<<1];
        ret=query(k,rson);
    }
    PushUP(rt);
    return ret;
}

int main()
{
    int i,n,k;
    while(scanf("%d%d",&n,&k)!=EOF)
    {
        for(i=0;i<n;i++)
          scanf("%s%d",nam[i],&next[i]);
        build(0,n-1,1);
        i=0;
        while(a[i]<=n) i++;
        int p=a[i-1];
        int MAX=b[i-1];
        int id;
        int t=n;
        for(i=0;i<p;i++)
        {
            t--;
            id=query(k,0,n-1,1);
            //id表示的是初始的位置在哪
            if(t==0) break;
            if(next[id]<0)//向前
            {
               k = ((k-1+next[id])%t+t)%t+1;
            }
            else//向后
            {//k表示的剩余人中的第几个
               k = (k-1+next[id]-1)%t+1;
            }
        }
        printf("%s %d\n",nam[id],MAX);
    }
    return 0;
}