Added spiral-matrix solution

Author: nhistory

spiral-matrix/nhistory.js

@@ -0,0 +1,45 @@
+var spiralOrder = function (matrix) {
+  // Edge case
+  if (matrix.length === 0) return [];
+
+  let result = [];
+  let rowStart = 0,
+    rowEnd = matrix.length - 1;
+  let colStart = 0,
+    colEnd = matrix[0].length - 1;
+
+  while (rowStart <= rowEnd && colStart <= colEnd) {
+    // Traverse right
+    for (let col = colStart; col <= colEnd; col++) {
+      result.push(matrix[rowStart][col]);
+    }
+    rowStart++;
+
+    // Traverse down
+    for (let row = rowStart; row <= rowEnd; row++) {
+      result.push(matrix[row][colEnd]);
+    }
+    colEnd--;
+
+    // Traverse left (check if rowStart <= rowEnd to avoid duplicates)
+    if (rowStart <= rowEnd) {
+      for (let col = colEnd; col >= colStart; col--) {
+        result.push(matrix[rowEnd][col]);
+      }
+      rowEnd--;
+    }
+
+    // Traverse up (check if colStart <= colEnd to avoid duplicates)
+    if (colStart <= colEnd) {
+      for (let row = rowEnd; row >= rowStart; row--) {
+        result.push(matrix[row][colStart]);
+      }
+      colStart++;
+    }
+  }
+
+  return result;
+};
+
+// TC: O(m*n)
+// SC: O(m*n)