Partition Equal Subset Sum

mediumcodingAlgorithmsDynamic ProgrammingArrays~30 min

Asked at Google, Meta

Overview

Given an integer array nums, return true if you can partition it into two subsets with equal sum.

Constraints

1 <= nums.length <= 200
1 <= nums[i] <= 100

Examples

canPartition([1, 5, 11, 5]); // => true  ([1,5,5] and [11])
canPartition([1, 2, 3, 5]);  // => false

Solution

Reveal solution

function canPartition(nums) {
  const total = nums.reduce((a, b) => a + b, 0);
  if (total % 2 !== 0) return false;
  const target = total / 2;
  const dp = new Set([0]);
  for (const num of nums) {
    const next = new Set(dp);
    for (const s of dp) {
      if (s + num === target) return true;
      next.add(s + num);
    }
    dp.clear();
    for (const v of next) dp.add(v);
  }
  return dp.has(target);
}

Resources

Partition Equal Subset Sum — LeetCode

partition-equal-subset-sum.js

Partition Equal Subset Sum

mediumcodingAlgorithmsDynamic Programming

Overview

Given an integer array nums, return true if you can partition it into two subsets with equal sum.

Constraints

1 <= nums.length <= 200
1 <= nums[i] <= 100

Examples

canPartition([1, 5, 11, 5]); // => true  ([1,5,5] and [11])
canPartition([1, 2, 3, 5]);  // => false

Solution

Reveal solution

function canPartition(nums) {
  const total = nums.reduce((a, b) => a + b, 0);
  if (total % 2 !== 0) return false;
  const target = total / 2;
  const dp = new Set([0]);
  for (const num of nums) {
    const next = new Set(dp);
    for (const s of dp) {
      if (s + num === target) return true;
      next.add(s + num);
    }
    dp.clear();
    for (const v of next) dp.add(v);
  }
  return dp.has(target);
}

Resources

Partition Equal Subset Sum — LeetCode

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