883.三维体投影面积

caution

原题链接：https://leetcode-cn.com/problems/projection-area-of-3d-shapes/

思路

• xy：grid[i][j] > 0 就加1
• yz：按列找最大值
• zx：按行找最大值

代码

class Solution {
public:
    int projectionArea(vector<vector<int>>& grid) {
        // xy
        int xy = 0;
        for (int i = 0; i < grid.size(); i++) {
            for (int j = 0; j < grid[0].size() ;j++ ) {
                if (grid[i][j] > 0) xy ++;
            }
        }

        int yz = 0;
        for (int i = 0; i < grid[0].size(); i++) {
            int myz = 0;
            for (int j = 0; j < grid.size(); j++) {
                myz = max(myz, grid[j][i]);
            }
            yz += myz;
        }

        int zx = 0;
        for (int i =0 ; i < grid.size(); i++) {
            int mzx = 0;
            for (int j = 0; j < grid[0].size(); j++) {
                mzx = max(mzx, grid[i][j]);
            }
            zx += mzx;
        }
        return xy + yz + zx;
    }
};