LeetCode: Trapping Rain Water

继续不争气看网上答案。。

class Solution {
public:
    int trap(int A[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if (n < 2) return 0;
        vector<int> left(n, A[0]);
        vector<int> right(n, A[n-1]);
        int ret = 0;
        for (int i = 1; i < n; i++) left[i] = max(left[i-1], A[i]);
        for (int i = n-2; i >= 0; i--) right[i] = max(right[i+1], A[i]);
        for (int i = 1; i < n-1; i++) {
            int tmp = min(left[i], right[i]) - A[i];
            ret += tmp > 0? tmp : 0;
        }
        return ret;
    }
};

 C#

public class Solution {
    public int Trap(int[] height) {
        int n = height.Length;
        if (n < 2) return 0;
        int[] left = new int[n];
        int[] right = new int[n];
        for (int i = 0; i < n; i++) {
            left[i] = height[0];
            right[i] = height[n-1];
        }
        int ans = 0;
        for (int i = 1; i < n; i++) left[i] = Math.Max(left[i-1], height[i]);
        for (int i = n-2; i >= 0; i--) right[i] = Math.Max(right[i+1], height[i]);
        for (int i = 1; i < n-1; i++) {
            int tmp = Math.Min(left[i], right[i]) - height[i];
            ans += tmp > 0? tmp : 0;
        }
        return ans;
    }
}