题目: Given an unsorted integer array, find the first missing positive integer. For example,Given [1,2,0] return 3,and [3,4,-1,1] return 2. Your algorithm should run in O(n) time and uses constant space. 给定一个没有排好序的数组.找出其中第一个消逝的正整数.例如 [1,2,5,4]那就是缺3. 思路…