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  • 螺旋矩阵II

    Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

    Example:

    Input: 3
    Output:
    [
    [ 1, 2, 3 ],
    [ 8, 9, 4 ],
    [ 7, 6, 5 ]
    ]

    来源:力扣(LeetCode)
    链接:https://leetcode-cn.com/problems/spiral-matrix-ii
    著作权归领扣网络所有。商业转载请联系官方授权,非商业转载请注明出处。

    建立top,bottom,left,right四个边界,创建n*n二维数组并逆时针赋值,当到达边界时,上、左边界自增,右、下边界自减,当top>bottom或left>right时,结束循环。代码如下:

        public int[][] generateMatrix(int n) {
            int[][] res = new int[n][n];
            int top = 0;
            int bottom = n-1;
            int left = 0;
            int right = n-1;
            int target = 1;
            //看了一下题解,有的大佬把判断循环是否结束的语句设置为target<=n*n
            while(top <= bottom || left <= right)
            {
                //从左往右
                for(int i = left; i <= right; i++)
                {
                    res[top][i] = target++;
                }
                top++;
                //从上往下
                for(int i = top; i <= bottom; i++)
                {
                    res[i][right] = target++;
                }
                right--;
                //从右往左
                for(int i = right; i >= left; i--)
                {
                    res[bottom][i] = target++;
                }
                bottom--;
                //从下往上
                for(int i = bottom; i >= top; i--)
                {
                    res[i][left] = target++;
                }
                left++;
                
            }
            return res;
        }
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  • 原文地址:https://www.cnblogs.com/WakingShaw/p/11581254.html
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