[LeetCode]Spiral Matrix

题目

Number: 54
Difficulty: Medium
Tags: Array

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

For example,
Given the following matrix:

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

You should return [1,2,3,6,9,8,7,4,5].

题解

螺旋数组问题。

常规方法就是分四条边考虑，注意各种边界。

代码

vector<int> spiralOrder(vector<vector<int>>& matrix) {
    vector<int> res;
    if(matrix.empty())
        return res;
    int m = matrix.size(), n = matrix[0].size();
    int max = m * n, i = 0, j = 0, cur = 0, level = 0;
    while(cur < max){
        while(j < n - level && cur < max){
            res.push_back(matrix[i][j]);
            cur++;
            j++;
        }
        j--;
        i++;
        while(i < m-level && cur < max){
            res.push_back(matrix[i][j]);
            cur++;
            i++;
        }
        i--;
        j--;
        while(j >= level && cur < max){
            res.push_back(matrix[i][j]);
            cur++;
            j--;
        }
        j++;
        i--;
        while(i > level && cur < max){
            res.push_back(matrix[i][j]);
            cur++;
            i--;
        }
        i++;
        j++;
        level++;
    }
    return res;
}