js-concepts: leetcode prob.977-Squares of a Sorted Array with O(n)

Author: baochau.dinh

LeetCode/977. Squares of a Sorted Array/index.js

@@ -0,0 +1,41 @@
+var sortedSquares = function(nums) {
+  if (nums.length === 1) return [Math.pow(nums[0], 2)];
+  let firstPositiveIdx = -1;
+  for (let i = 0; i < nums.length; i++) {
+    if (nums[i] >= 0) {
+      firstPositiveIdx = i;
+      break;
+    }
+  }
+  let squares = nums.map(item => Math.pow(item, 2));
+  let result = [];
+
+  if (nums[0] >= 0) {
+    return squares;
+  } else if (nums[nums.length - 1] <= 0) {
+    return squares.reverse();
+  } else {
+    let first = firstPositiveIdx - 1, second = firstPositiveIdx;
+    while (first >= 0 && second < nums.length) {
+      if (squares[first] <= squares[second]) {
+        result.push(squares[first]);
+        first--;
+      } else {
+        result.push(squares[second]);
+        second++;
+      }
+    }
+    while (first >= 0) {
+      result.push(squares[first]);
+      first--;
+    }
+    while (second < nums.length) {
+      result.push(squares[second]);
+      second++;
+    }
+  }
+
+  return result;
+}
+
+console.log(sortedSquares([-3, 0, 2]));