LeetCode——Spiral Matrix II

最新推荐文章于 2021-06-06 17:00:57 发布

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本文介绍了一个C++实现的螺旋矩阵生成算法，该算法能够根据给定的整数n生成一个n×n的矩阵，矩阵元素从1到n²按螺旋顺序填充。通过巧妙地使用方向数组和边界检查实现了螺旋式的填充过程。

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 ]
]

» Solve this problem

修改了Spiral Matrix的代码。

class Solution {
public:
    vector<vector<int> > generateMatrix(int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<vector<int> > ans;
        for (int i = 0; i < n; i++) {
            vector<int> t = vector<int>(n, -1);
            ans.push_back(t);
        }
        int step[][2] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
        int dir = 0, x = 0, y = 0;   
        for (int i = 1; i <= n * n; i++) {            
            ans[x][y]= i;
            
            if (x + step[dir][0] == n || x + step[dir][0] < 0 || 
                y + step[dir][1] == n || y + step[dir][1] < 0 ||
                ans[x + step[dir][0]][y + step[dir][1]] != -1) {
                    dir = dir == 3 ? 0 : dir + 1;
                }
            x += step[dir][0];
            y += step[dir][1];
        }
        return ans;
    }
};