摘要：42. Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after rain 阅读全文

摘要：41. 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 algorit 阅读全文