leetcode42 接雨水

简介

接雨水.

简单思路

排序, 依次选择最高的柱子,所围城的池塘高度

code

class Solution {
public:

    struct zhuzi{
        int height;
        int index;
    };
    bool static cmp(const struct zhuzi &a, const struct zhuzi &b) {
        return a.height > b.height;
    }
    int trap(vector<int>& height) {
        if(height.size() < 2) {
            return 0;
        }
        int sum = 0;
        vector<struct zhuzi> zh;
        int index = 0;
        for(auto it : height) {
            zh.push_back({it, index});
            index++;
        }
        sort(zh.begin(), zh.end(), cmp);
        vector<bool> check(zh.size(), false);
        int minIndex = 0;
        int maxIndex = 0;
        for(int i =0; i < zh.size(); i++) {
            if(i == 0) {
                int a = zh[i].height;
                int b = zh[i+1].height;
                int abminH = min(a, b);
                int aI = zh[i].index;
                int bI = zh[i+1].index;
                int minab = min(aI, bI);
                minIndex = minab;
                int maxab = max(aI, bI);
                maxIndex = maxab;
                for(int j = minab + 1; j < maxab; j++){
                    sum += abminH - height[j];
                    check[j] = true;
                }
                i++;
            }else{
                
                int c = zh[i].height;
                int ci = zh[i].index;
                if(ci >= minIndex && ci <= maxIndex ) {
                    continue;
                }
                if(ci < minIndex) {
                    for(int j = ci + 1; j < minIndex; j++) {
                        sum += c - height[j];
                        check[j] = true;
                    }
                    minIndex = ci;
                }else if(ci > maxIndex){
                    for(int j = maxIndex + 1; j < ci; j++) {
                        sum += c - height[j];
                        check[j] = true;
                    }
                    maxIndex = ci;
                }
            }
        }
        return sum;
    }
};

  class Solution {
    public int trap(int[] height) {
        if(height == null || height.length == 0) {
            return 0;
        }
        int ans = 0;
        int size = height.length;
        int [] left_max = new int[size];
        int [] right_max = new int[size];
        left_max[0] = height[0];
        for(int i=1; i<size; i++){
            left_max[i] = Math.max(height[i], left_max[i-1]);
        }
        right_max[size - 1] = height[size - 1];
        for(int i = size - 2; i>=0;  i--) {
            right_max[i] = Math.max(height[i], right_max[i + 1]);
        }
        for(int i=1; i<size - 1; i++) {
            ans += Math.min(left_max[i], right_max[i]) - height[i];
        }
        return ans;
    }
}