Find n'th Digit of a Number -- 8 kyu

原题

http://www.codewars.com/kata/find-nth-digit-of-a-number/train/cpp

题目

The function findDigit takes two numbers as input, num and nth. It outputs the nth digit of num (counting from right to left).

• If num is negative, ignore its sign and treat it as a positive value.
• If nth is not positive, return -1.
• Keep in mind that 42 = 00042. This means that findDigit(42, 5) would return 0.

Example:

findDigit(5673, 4)
returns 5
findDigit(129, 2)
returns 2
findDigit(-2825, 3)
returns 8
findDigit(-456, 4)
returns 0
findDigit(0, 20)
returns 0
findDigit(65, 0)
returns -1
findDigit(24, -8)

分析

取出第n位上的数值的绝对值，可以将数据除以10(n-1)次方后和10取余得到该值

代码

#include <cmath>int findDigit(int num, int nth){    return nth <=0?-1:int(abs(num)/pow(10,nth-1))%10;}