[leetcode] 59. Spiral Matrix II

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本文提供了一种解决方案来生成一个n阶矩阵，并以螺旋顺序填充从1到n²的整数。详细步骤和代码实现将帮助读者理解和解决相关问题。

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

For example,
Given n = 3,

You should return the following matrix:

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

这道题是螺旋形生成矩阵，题目难度为Medium。

题目和第54题相关，基本的处理方法是类似的，有疑问的同学请查看第54题（传送门）。具体代码：

class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        vector<vector<int>> rst(n, vector<int>(n, 0));
        int lRow = 0, rRow = n - 1;
        int lCol = 0, rCol = n - 1;
        int pos = 0, state = 0, cnt = 1;
        while(lRow<=rRow && lCol<=rCol) {
            switch(state) {
                case 0: {
                    pos = lCol;
                    while(pos <= rCol) 
                        rst[lRow][pos++] = cnt++;
                    lRow++;
                    break;
                }
                case 1: {
                    pos = lRow;
                    while(pos <= rRow)
                        rst[pos++][rCol] = cnt++;
                    rCol--;
                    break;
                }
                case 2: {
                    pos = rCol;
                    while(pos >= lCol)
                        rst[rRow][pos--] = cnt++;
                    rRow--;
                    break;
                }
                default: {
                    pos = rRow;
                    while(pos >= lRow)
                        rst[pos--][lCol] = cnt++;
                    lCol++;
                    break;
                }
            }
            state = (state + 1) % 4;
        }
        return rst;
    }
};