LeetCode：Trapping Rain Water

標籤：leetcode

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 raining.

For example,
Given [0,1,0,2,1,0,1,3,2,1,2,1], return 6.

The above elevation map is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rain water (blue section) are being trapped.Thanks Marcos for contributing this image!

// https://oj.leetcode.com/problems/trapping-rain-water/// Author : Chao Zeng// Date   : 2015-2-11class Solution {public:    int trap(int A[], int n) {        int ans = 0;        int maxnum = A[0];        int flag = 0;        for (int i = 0; i < n; i++){            if (maxnum < A[i]){                maxnum = A[i];                flag = i;            }        }                int currentmaxnum = A[0];        for (int i = 0; i < flag ; i++){            if (currentmaxnum < A[i]){                currentmaxnum = A[i];            }            if (A[i] < maxnum && A[i] < currentmaxnum){                ans += currentmaxnum - A[i];            }        }        currentmaxnum = A[n - 1];        for (int i = n -1; i > flag; i--){            if (currentmaxnum < A[i]){                currentmaxnum = A[i];            }            if (A[i] < maxnum && A[i] < currentmaxnum){                ans += currentmaxnum - A[i];            }        }        return ans;    }};

 

LeetCode：Trapping Rain Water