[数组]数组元素置换方法

数组中未出现的最小正整数 http://www.nowcoder.com/discuss/1739

https://leetcode.com/problems/contains-duplicate/

http://www.nowcoder.com/practice/623a5ac0ea5b4e5f95552655361ae0a8?rp=3&ru=/ta/coding-interviews