剑指 Offer 29. 顺时针打印矩阵（简单）

我不是女神ヾ 2022-09-10 12:07 109阅读 0赞

Leetcode链接：[剑指 Offer 29. 顺时针打印矩阵][Offer 29.]

### 题目描述 ###

输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字。

示例 1：

> 输入：matrix = \[\[1,2,3\],\[4,5,6\],\[7,8,9\]\]  
> 输出：\[1,2,3,6,9,8,7,4,5\]

示例 2：

> 输入：matrix = \[\[1,2,3,4\],\[5,6,7,8\],\[9,10,11,12\]\]  
> 输出：\[1,2,3,4,8,12,11,10,9,5,6,7\]

限制：

> 0 <= matrix.length <= 100  
> 0 <= matrix\[i\].length <= 100

### 源码 ###

class Solution {
        
        public int[] spiralOrder(int[][] matrix) {
        
            int m = matrix.length;
            if(m == 0) return new int[0]; 
            int n = matrix[0].length;
            if(n == 0) return new int[0];
    
            int up = 0;
            int down = m - 1;
            int left = 0;
            int right = n - 1;
    
            int index = 0;
            int[] res = new int[m * n];
    
            while(left <= right && up <= down){
        
                
                for(int col = left; col <= right; col ++){
        
                    res[index ++] = matrix[up][col];
                }
                up ++;
    
                for(int row = up; row <= down; row++){
        
                    res[index ++] = matrix[row][right];
                }
                right --;
    
                if(left > right || up > down) break;
    
                for(int col = right; col >= left; col --){
        
                    res[index ++] = matrix[down][col];
                }
                down --;
    
                for(int row = down; row >= up; row --){
        
                    res[index ++] = matrix[row][left];
                }
                left ++;
            }
    
            return res;
        }
    }

[Offer 29.]: https://leetcode-cn.com/problems/shun-shi-zhen-da-yin-ju-zhen-lcof/