POJ 2081 Recaman's Sequence

http://poj.org/problem?id=2081

打表.

#include <stdio.h>
int numbers[500001];
bool flags[500001*10]={false};
int main()
{
    int i;
    numbers[0]=0;
    flags[0]=true;
    numbers[1]=1;
    flags[1]=true;
    for(i=2;i<=500000;i++) {
        if(numbers[i-1]-i>0&&(flags[numbers[i-1]-i]==false)) {
            numbers[i]=numbers[i-1]-i;
            flags[numbers[i]]=true;
        } else {
            numbers[i]=numbers[i-1]+i;
            flags[numbers[i]]=true;
        }
    }
    int k;
    while(scanf("%d",&k)!=EOF) {
        if(k==-1)    return 0;
        printf("%d\n",numbers[k]);
    }
    return 0;
}