rearrange-array-elements-by-sign

coding_interviews/leetcode/medium/rearrange-array-elements-by-sign/rearrange-array-elements-by-sign.js

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+/*
+You are given a 0-indexed integer array nums of even length consisting of an equal number of positive and negative integers.
+
+You should rearrange the elements of nums such that the modified array follows the given conditions:
+
+Every consecutive pair of integers have opposite signs.
+For all integers with the same sign, the order in which they were present in nums is preserved.
+The rearranged array begins with a positive integer.
+Return the modified array after rearranging the elements to satisfy the aforementioned conditions.
+
+Example 1:
+Input: nums = [3,1,-2,-5,2,-4]
+Output: [3,-2,1,-5,2,-4]
+Explanation:
+The positive integers in nums are [3,1,2]. The negative integers are [-2,-5,-4].
+The only possible way to rearrange them such that they satisfy all conditions is [3,-2,1,-5,2,-4].
+Other ways such as [1,-2,2,-5,3,-4], [3,1,2,-2,-5,-4], [-2,3,-5,1,-4,2] are incorrect because they do not satisfy one or more conditions.  
+
+Example 2:
+Input: nums = [-1,1]
+Output: [1,-1]
+Explanation:
+1 is the only positive integer and -1 the only negative integer in nums.
+So nums is rearranged to [1,-1].
+*/
+
+function isPositive(num) {
+  return num > 0;
+}
+
+export function rearrangeArray(nums) {
+  const negative = [];
+  const positive = [];
+
+  nums.forEach((num) => {
+    if (isPositive(num)) {
+      positive.push(num);
+    } else {
+      negative.push(num);
+    }
+  });
+
+  const rearrangeArray = [];
+
+  for (let i = 0; i < negative.length; i++) {
+    rearrangeArray.push(positive[i]);
+    rearrangeArray.push(negative[i]);
+  }
+
+  return rearrangeArray;
+}

coding_interviews/leetcode/medium/rearrange-array-elements-by-sign/tests/rearrange-array-elements-by-sign.test.js

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+import { describe, expect, it } from 'vitest';
+import { rearrangeArray } from '../rearrange-array-elements-by-sign';
+
+describe('rearrangeArray', () => {
+  it('', () => {
+    expect(rearrangeArray([3, 1, -2, -5, 2, -4])).toEqual([
+      3, -2, 1, -5, 2, -4,
+    ]);
+  });
+
+  it('', () => {
+    expect(rearrangeArray([-1, 1])).toEqual([1, -1]);
+  });
+});