leetcode讲解--892. Surface Area of 3D Shapes

题目On a N * N grid, we place some 1 * 1 * 1 cubes.Each value v = grid[i][j] represents a tower of v cubes placed on top of grid cell (i, j).Return the total surface area of the resulting shapes.Example 1:Input: [[2]]Output: 10Example 2:Input: [[1,2],[3,4]]Output: 34Example 3:Input: [[1,0],[0,2]]Output: 16Example 4:Input: [[1,1,1],[1,0,1],[1,1,1]]Output: 32Example 5:Input: [[2,2,2],[2,1,2],[2,2,2]]Output: 46Note:1 <= N <= 500 <= grid[i][j] <= 50题目地址讲解这道题感觉还挺难的，不应该放在简单题里面。主要是考察分类讨论的能力，corner case非常之多，对分类讨论的能力要求很高。调试好久才过。java代码class Solution { public int surfaceArea(int[][] grid) { int result = 0; for(int i=0;i<grid.length;i++){ for(int j=0;j<grid.length;j++){ if(i==0){ if(j==0){ if(grid[i][j]<=1){ result += 6grid[i][j]; }else{ result += 6+4(grid[i][j]-1); } }else{ if(grid[i][j]<=1){ result += grid[i][j]6-2(Math.min(grid[i][j],grid[i][j-1])); }else{ result += 6+4*(grid[i][j]-1)-2*(Math.min(grid[i][j],grid[i][j-1])); } } }else{ if(j==0){ if(grid[i][j]<=1){ result += grid[i][j]6-2(Math.min(grid[i][j],grid[i-1][j])); }else{ result += 6+4*(grid[i][j]-1)-2*(Math.min(grid[i][j],grid[i-1][j])); } }else{ if(grid[i][j]<=1){ result += grid[i][j]6-2(Math.min(grid[i][j],grid[i-1][j]))-2*(Math.min(grid[i][j],grid[i][j-1])); }else{ result += 6+4*(grid[i][j]-1)-2*(Math.min(grid[i][j],grid[i-1][j]))-2*(Math.min(grid[i][j],grid[i][j-1])); } } } } } return result; }}