Spirally_traversing_a_matrix.java

// { Driver Code Starts
import java.io.*;
import java.util.*;

class GFG {
  public static void main(String args[]) throws IOException {
    Scanner sc = new Scanner(System.in);
    int t = sc.nextInt();

    while (t-- > 0) {
      int r = sc.nextInt();
      int c = sc.nextInt();

      int matrix[][] = new int[r][c];

      for (int i = 0; i < r; i++) {
        for (int j = 0; j < c; j++)
          matrix[i][j] = sc.nextInt();
      }
      Solution ob = new Solution();
      ArrayList<Integer> ans = ob.spirallyTraverse(matrix, r, c);
      for (Integer val : ans)
        System.out.print(val + " ");
      System.out.println();
    }
  }
}

class Solution {
  static ArrayList<Integer> spirallyTraverse(int matrix[][], int r, int c) {
    ArrayList<Integer> ans = new ArrayList<>();
    int dir = 0;
    int top = 0, down = r - 1, left = 0, right = c - 1;
    while (top <= down && left <= right) {
      if (dir == 0) {
        for (int i = left; i <= right; i++) {
          ans.add(matrix[top][i]);
        }
        top++;
      } else if (dir == 1) {
        for (int i = top; i <= down; i++) {
          ans.add(matrix[i][right]);
        }
        right--;
      } else if (dir == 2) {
        for (int i = right; i >= left; i--) {
          ans.add(matrix[down][i]);
        }
        down--;
      } else if (dir == 3) {
        for (int i = down; i >= top; i--) {
          ans.add(matrix[i][left]);
        }
        left++;
      }
      dir = (dir + 1) % 4;
    }
    return ans;
  }
}