solution: spiral matrix

Author: Jeongwon Na

spiral-matrix/njngwn.java

@@ -0,0 +1,44 @@
+// Time Complexity: O(m+n), m: matrix.length, n: matrix[0].length
+// Space Complexity: O(m*n), m: matrix.length, n: matrix[0].length, because of arraylist for output
+class Solution {
+    public List<Integer> spiralOrder(int[][] matrix) {
+        int rowMin = 0;
+        int rowMax = matrix.length-1;
+        int colMin = 0;
+        int colMax = matrix[0].length-1;
+
+        ArrayList<Integer> orderedElements = new ArrayList<>();
+
+        while (rowMin <= rowMax && colMin <= colMax) {
+            // left to right
+            for (int col = colMin; col <= colMax; ++col) {
+                orderedElements.add(matrix[rowMin][col]);
+            }
+            rowMin++;
+
+            // top to bottom
+            for (int row = rowMin; row <= rowMax; ++row) {
+                orderedElements.add(matrix[row][colMax]);
+            }
+            colMax--;
+
+            // right to left
+            if (rowMin <= rowMax) {
+                for (int col = colMax; col >= colMin; --col) {
+                    orderedElements.add(matrix[rowMax][col]);
+                }
+            }
+            rowMax--;
+
+            // bottom to top
+            if (colMin <= colMax) {
+                for (int row = rowMax; row >= rowMin; --row) {
+                    orderedElements.add(matrix[row][colMin]);
+                }
+            }
+            colMin++;
+        }
+
+        return orderedElements;
+    }
+}