【Leetcode】42.接雨水C++

/*
给定 n 个非负整数表示每个宽度为 1 的柱子的高度图，计算按此排列的柱子，下雨之后能接多少雨水。
*/

#include "iostream"

#include "stack"

#include "vector"

using namespace std;

class Solution
{
public:

    int trap(vector<int> &height)
    {
        if (height.size() < 3)
        {
            return 0;
        }

        int i = 0;
        int ans = 0, n;
        int max_index = 0;
        for (i = 1; i < height.size(); i++)
        {
            if (height[i] > height[max_index])
            {
                max_index = i;
            }
        }

        stack<int> h;

        // 从左向右
        i = 0;
        int left;
        while (height[i] < height[i + 1])
        {
            i++;
            if (i + 1 > max_index)
            {
                break;
            }
        }
        left = height[i];
        for (i++; i <= max_index; i++)
        {
            n = height[i];
            if (n < left)
            {
                h.push(n);
            }
            else
            {
                while (!h.empty())
                {
                    ans += left - h.top();
                    h.pop();
                }
                left = n;
            }
        }

        // 从右向左
        i = height.size() - 1;
        int right;
        while (height[i] < height[i - 1] && i > max_index)
        {
            i--;
            if (i - 1 < max_index)
            {
                break;
            }
        }
        right = height[i];
        for (i--; i >= max_index; i--)
        {
            n = height[i];
            if (n < right)
            {
                h.push(n);
            }
            else
            {
                while (!h.empty())
                {
                    ans += right - h.top();
                    h.pop();
                }
                right = n;
            }
        }

        return ans;
    }
};

int main(int argc, char const *argv[])
{
    vector<int> height;
    int x;

    while (true)
    {
        cin >> x;
        height.push_back(x);
        if (cin.get() == '\n')
            break;
    }

    Solution so;
    x = so.trap(height);

    cout << x << endl;

    return 0;
}