Codeforces Round #237 (Div. 2) B. Marathon（卡long long）

题目：http://codeforces.com/contest/404/problem/B

#include <iostream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
using namespace std;

int main()
{
    __int64 g;   //g一定要是长整形，因为数据会超int.这个也是错误的最主要原因
    int n, i;
    double a, d, x, y, sum, cnt;
    while(~scanf("%lf%lf%d", &a, &d, &n))
    {
        sum = (double)(a*4);
        for(i = 1; i <= n; i++)
        {
            cnt = (double)i*d;

            g =(long long)(cnt/sum); //这里一定把要转换的部分加上括号
            cnt = (double)(cnt-g*sum);
            if(cnt-a<=0)
            {
                y = 0;
                x = cnt;
            }
            else if(cnt-2*a<=0)
            {
                x = a;
                y = cnt-a;  
            }
            else if(cnt-3*a<=0)
            {
                x = a-(cnt-2*a);
                y = a;
            }
            else
            {
                x = 0;
                y = a-(cnt-3*a);
            }
            printf("%.10lf %.10lf\n", x, y);
        }
    }
    return 0;
}