LeetCode 54. Spiral Matrix

 54. Spiral Matrix

Given an m x n matrix, return all elements of the matrix in spiral order.

 

Example 1:

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

Example 2:

Input: matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
Output: [1,2,3,4,8,12,11,10,9,5,6,7]

 

Constraints:

• m == matrix.length
• n == matrix[i].length
• 1 <= m, n <= 10
• -100 <= matrix[i][j] <= 100

	class Solution {
	public:
	vector<int> spiralOrder(vector<vector<int>>& matrix) {
	vector<int> ans;
	int m = matrix.size();
	int n = matrix[0].size();
	vector<vector<bool>> check(m, vector<bool>(n, false));
	int x = 0;
	int y = 0;
	int dx = 0;
	int dy = 1;
	while(ans.size() < m * n){
	ans.push_back(matrix[x][y]);
	check[x][y] = true;
	x += dx;
	y += dy;
	// right
	if(x >= m or (x < m and dx == 1 and check[x][y])){x--; y--; dx = 0; dy = -1;}
	if(x < 0 or (x >= 0 and dx == -1 and check[x][y])){x++; y++; dx = 0; dy = 1;}
	if(y >= n or (y < n and dy == 1 and check[x][y])){x++; y--; dx = 1; dy = 0;}
	if(y < 0 or (y >= 0 and dy == -1 and check[x][y])) {x--; y++; dx = -1; dy = 0;}
	}
	return ans;
	}
	};

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