题目

思路

1. 直接遍历就行.

代码

public int[] findDiagonalOrder(int[][] mat) {
    
        int[] ans = new int[mat.length * mat[0].length];
        int index = 0;
        //在matIt traverses the rows and columns inside
        int row=0;
        int col=0;
        //Top right or bottom left 右上true 左下false
        boolean flag = true;
        while (row<mat.length && col<mat[0].length){
    
            if(flag){
    
                while (row>=0 && col<mat[0].length){
    
                    ans[index++] = mat[row--][col++];
                }
                col--;
                row++;
                //move right first
                if(col+1<mat[0].length) col++;
                else row++;
                flag=false;
            }else {
    
                while(row<mat.length && col>=0){
    
                    ans[index++] = mat[row++][col--];
                }
                row--;
                col++;
                //Move down first
                if(row+1<mat.length) row++;
                else col++;
                flag=true;
            }
        }
        return ans;
    }