Spiral Matrix
Problem
Given aNXN matrix, starting from the upper right corner of the matrix start printingvalues in a counter-clockwise fashion.
E.g.: Consider N = 4
Matrix= {a, b, c, d,
e, f, g, h,
i, j, k, l,
m, n, o, p}
Your function should output: dcbaeimnoplhgfjk
Solution
1 public ArrayList<Integer> spiralOrder(int[][] matrix) { 2 ArrayList<Integer> res = new ArrayList<Integer>(); 3 4 if(matrix == null || matrix.length == 0) { 5 return res; 6 } 7 8 int row = matrix.length; 9 int col = matrix[0].length; 10 11 int x = 0; 12 int y = 0; 13 while(row > 0 && col > 0) { 14 //if row or col == 1, no circle can be found 15 if(row == 1) { 16 for(int i=0; i<col; i++) { 17 res.add(matrix[x][y++]); 18 } 19 break; 20 } 21 if(col == 1) { 22 for(int i=0; i<row; i++) { 23 res.add(matrix[x++][y]); 24 } 25 break; 26 } 27 28 //row left to right 29 for(int i=0; i<col-1; i++) { 30 res.add(matrix[x][y++]); 31 } 32 //col high to low 33 for(int i=0; i<row-1; i++) { 34 res.add(matrix[x++][y]); 35 } 36 //row right to left 37 for(int i=0; i<col-1; i++) { 38 res.add(matrix[x][y--]); 39 } 40 //col low to high 41 for(int i=0; i<row-1; i++) { 42 res.add(matrix[x--][y]); 43 } 44 45 row = row - 2; 46 col = col - 2; 47 x++; 48 y++; 49 50 } 51 52 return res; 53 }