Spiral Order Matrix I - The Coding Shala

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Spiral Order Matrix I Interview Bit Solution

Given a matrix of m * n elements (m rows, n columns), return all elements of the matrix in spiral order.
Spiral Order Matrix Java Program - The Coding Shala

 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]

Solution(Java):

Take four variables top, bottom, left and right. Start printing with the top then right then bottom and then left. Increase the values of variables after printing each row and columns.



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public class Solution {
    // DO NOT MODIFY THE LIST. IT IS READ ONLY
    public ArrayList<Integer> spiralOrder(final List<ArrayList<Integer>> A) {
        ArrayList<Integer> ans = new ArrayList<Integer>();
        int t = 0;
        int b = A.size()-1;
        int l = 0;
        int r = A.get(0).size()-1;
       // System.out.println(b+" "+r);
        int dir = 1;
        int tmp = 0;
        while(t<=b && l<=r){
            if(dir == 1){
                for(int i = l; i<= r; i++){
                    ans.add(A.get(t).get(i));
                }
                   // System.out.println(ans.get(tmp)+" "); tmp++;
                    dir = 2;
                    t++;
            }else if(dir == 2){
                for(int i=t;i<=b;i++){
                    ans.add(A.get(i).get(r));}
                   // System.out.println(ans.get(tmp)+" "); tmp++;
                    dir = 3;
                    r--;
                //}
            }else if(dir == 3){
                for(int i=r;i>=l;i--){
                    ans.add(A.get(b).get(i));}
                    //System.out.println(ans.get(tmp)+" "); tmp++;
                    dir = 4;
                    b--;
               // }
            }else if(dir == 4){
                for(int i=b;i>=t;i--){
                    ans.add(A.get(i).get(l));}
                   // System.out.println(ans.get(tmp)+" "); tmp++;
                    dir = 1;
                    l++;
               // }
            }
        }
        return ans;
    }
}



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