54. Spiral Matrix

Problem Statement

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

Intuition

Implementation

Links

https://leetcode.com/problems/spiral-matrix/description/

Video Links

https://www.youtube.com/watch?v=3Zv-s9UUrFM

Approach 1:

C++

class Solution {
public:
    vector<int> spiralOrder(vector<vector<int>>& arr) {
        vector<int> ans;
        int m = arr.size();
        int n = arr[0].size();
        int top = 0, bottom = m-1;
        int left = 0, right = n-1;

        while(left<=right and top<=bottom){
            for(int i=left; i<=right; i++){
                ans.push_back(arr[top][i]);
            }
            top++;

            for(int i=top; i<=bottom; i++){
                ans.push_back(arr[i][right]);
            }
            right--;

            // For row matrix check
            if(top<=bottom){
                for(int i=right; i>=left; i--){
                    ans.push_back(arr[bottom][i]);
                }
                bottom--;
            }
            // For col matrix check
            if(left<=right){
                for(int i=bottom; i>=top; i--){
                    ans.push_back(arr[i][left]);
                }
                left++;
            }
        }

        return ans;
    }
};

Approach 2:

C++

Approach 3:

C++

Approach 4:

C++

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