package matrix;

//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].

import java.util.ArrayList;

public class SpiralMatrix {

public ArrayList<Integer> spiralOrder(int[][] matrix) {

ArrayList<Integer> result = new ArrayList<Integer>();

if(matrix == null || matrix.length == 0) return result;

int m = matrix.length;

int n = matrix[0].length;

int x=0;

int y=0;

while(m>0 && n>0){

//if one row/column left, no circle can be formed

if(m==1){

for(int i=0; i<n; i++){

result.add(matrix[x][y++]);

}

break; }else if(n==1){

for(int i=0; i<m; i++){

result.add(matrix[x++][y]);

}

break; }

//below, process a circle

//top - move right

for(int i=0;i<n-1;i++){

result.add(matrix[x][y++]);

}

//right - move down

for(int i=0;i<m-1;i++){

result.add(matrix[x++][y]);

}

//bottom - move left

for(int i=0;i<n-1;i++){

result.add(matrix[x][y--]);

}

//left - move up

for(int i=0;i<m-1;i++){

result.add(matrix[x--][y]);

}

x++;

y++;

m=m-2;

n=n-2;

}

return result;

}

}