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| 1 | +/** |
| 2 | + * 2035. Partition Array Into Two Arrays to Minimize Sum Difference |
| 3 | + * https://leetcode.com/problems/partition-array-into-two-arrays-to-minimize-sum-difference/ |
| 4 | + * Difficulty: Hard |
| 5 | + * |
| 6 | + * You are given an integer array nums of 2 * n integers. You need to partition nums into two arrays |
| 7 | + * of length n to minimize the absolute difference of the sums of the arrays. To partition nums, |
| 8 | + * put each element of nums into one of the two arrays. |
| 9 | + * |
| 10 | + * Return the minimum possible absolute difference. |
| 11 | + */ |
| 12 | + |
| 13 | +/** |
| 14 | + * @param {number[]} nums |
| 15 | + * @return {number} |
| 16 | + */ |
| 17 | +var minimumDifference = function(nums) { |
| 18 | + const n = nums.length / 2; |
| 19 | + let result = Infinity; |
| 20 | + const totalSum = nums.reduce((sum, num) => sum + num, 0); |
| 21 | + const firstHalfSubsets = new Map(); |
| 22 | + |
| 23 | + for (let mask = 0; mask < (1 << n); mask++) { |
| 24 | + let size = 0; |
| 25 | + let subsetSum = 0; |
| 26 | + |
| 27 | + for (let i = 0; i < n; i++) { |
| 28 | + if ((mask & (1 << i)) !== 0) { |
| 29 | + size++; |
| 30 | + subsetSum += nums[i]; |
| 31 | + } |
| 32 | + } |
| 33 | + |
| 34 | + if (!firstHalfSubsets.has(size)) { |
| 35 | + firstHalfSubsets.set(size, []); |
| 36 | + } |
| 37 | + firstHalfSubsets.get(size).push(subsetSum); |
| 38 | + } |
| 39 | + |
| 40 | + for (const [size, sums] of firstHalfSubsets) { |
| 41 | + sums.sort((a, b) => a - b); |
| 42 | + } |
| 43 | + |
| 44 | + for (let mask = 0; mask < (1 << n); mask++) { |
| 45 | + let size = 0; |
| 46 | + let secondHalfSum = 0; |
| 47 | + |
| 48 | + for (let i = 0; i < n; i++) { |
| 49 | + if ((mask & (1 << i)) !== 0) { |
| 50 | + size++; |
| 51 | + secondHalfSum += nums[n + i]; |
| 52 | + } |
| 53 | + } |
| 54 | + |
| 55 | + const complementSize = n - size; |
| 56 | + const firstHalfSums = firstHalfSubsets.get(complementSize); |
| 57 | + const target = (totalSum - 2 * secondHalfSum) / 2; |
| 58 | + const closestIndex = binarySearch(firstHalfSums, target); |
| 59 | + |
| 60 | + if (closestIndex < firstHalfSums.length) { |
| 61 | + result = Math.min( |
| 62 | + result, Math.abs(totalSum - 2 * (secondHalfSum + firstHalfSums[closestIndex])) |
| 63 | + ); |
| 64 | + } |
| 65 | + |
| 66 | + if (closestIndex > 0) { |
| 67 | + result = Math.min( |
| 68 | + result, Math.abs(totalSum - 2 * (secondHalfSum + firstHalfSums[closestIndex - 1])) |
| 69 | + ); |
| 70 | + } |
| 71 | + } |
| 72 | + |
| 73 | + return result; |
| 74 | +}; |
| 75 | + |
| 76 | +function binarySearch(arr, target) { |
| 77 | + let left = 0; |
| 78 | + let right = arr.length - 1; |
| 79 | + |
| 80 | + if (right < 0) return 0; |
| 81 | + |
| 82 | + while (left < right) { |
| 83 | + const mid = Math.floor((left + right) / 2); |
| 84 | + |
| 85 | + if (arr[mid] < target) { |
| 86 | + left = mid + 1; |
| 87 | + } else { |
| 88 | + right = mid; |
| 89 | + } |
| 90 | + } |
| 91 | + |
| 92 | + return left; |
| 93 | +} |
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