美团点评2017秋招笔试编程题

#include<cstdio>
#include<iostream>
#include<math.h>
int main()
{
    int n;
    while(scanf("%d", &n) != EOF)
    {
        double result = pow(2,n-1);  //2的n-1次方
        printf("%d\n", int(result));
    }
    return 0;
}

#include<cstdio>
#include<iostream>
int main()
{
    int n,result;
    while(scanf("%d", &n) != EOF)
    {
        result = 1;
        if(n==1)
            printf("%d\n", 1);
        else
        {
            for(int i=1; i<n; i++)   //如果记不得pow()
                result *= 2;
            printf("%d\n", result);
        }

    }
    return 0;
}