LeetCode·59. Spiral Matrix II

题目：

59. Spiral Matrix II

Given a positive integer n, generate a square matrix filled with elements from 1 to n^2 in spiral order.

Example:

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

思路：

按层处理，每层处理一圈

代码：

class Solution {
public:
    vector<vector<int>> generateMatrix(int n) {
        vector<vector<int> > vec(n, vector<int>(n, 0));
        int row = n-1;
        int col = n-1;
        int x = 0;
        int y = 0;
        int value = 1;

        while(true){
            if(x > col)return vec;
            else if(x == col){
                vec[x][x] = value;
                return vec;
            }

            for(int i = x; i <= col; ++i)
                vec[y][i] = value++;

            for(int i = y+1; i <= row; ++i)
                vec[i][col] = value++;

            for(int i = col-1; i >= x; --i)
                vec[row][i] = value++;

            for(int i = row-1; i > y; --i)
                vec[i][x] = value++;

            ++x;++y;
            --row;--col;
        }

        return vec;
    }
};

结果：

一遍过，干净易懂，nice~~