leetcode 59. Spiral Matrix II-蒲公英云

leetcode 59. Spiral Matrix II

港控/mmm° 2022-08-21 04:19 248阅读 0赞

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 ]
]
class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        vector<vector<int>>matrix(n);
        if(n==0)
            return matrix;
        for (int i = 0; i < n; i++)
            matrix[i].resize(n);
        if (n == 1)
        {
            matrix[0][0] = 1;
            return matrix;
        }
        int k = 1;
        int off = 0;
        while (true)
        {
            for (int i = off; i < matrix[0].size() - off; i++)
            {
                matrix[off][i] =k++;
            }
            if (k == n*n + 1)
                return matrix;
            for (int i = off + 1; i < matrix.size() - off; i++)
            {
                matrix[i][matrix.size() - 1 - off] = k++;
            }
            for (int i = matrix.size() - 2 - off; i >= off; i--)
            {
                matrix[matrix.size() - 1 - off][i] = k++;
            }
            for (int i = matrix.size() - 2 - off; i >= off + 1; i--)
            {
                matrix[i][off] =  k++;
            }
            if (k == n*n + 1)
                return matrix;
            off++;
        }
    }
};