标签:Subset map return nums sum Partition 416 result total
package LeetCode_416 /** * 416. Partition Equal Subset Sum * https://leetcode.com/problems/partition-equal-subset-sum/description/ * * Given a non-empty array containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal. Note: Each of the array element will not exceed 100. The array size will not exceed 200. Example 1: Input: [1, 5, 11, 5] Output: true Explanation: The array can be partitioned as [1, 5, 5] and [11]. Example 2: Input: [1, 2, 3, 5] Output: false Explanation: The array cannot be partitioned into equal sum subsets. * */ class Solution { fun canPartition(nums: IntArray): Boolean { val total = nums.sum() if (total % 2 != 0) { return false } val result = dfs(0, 0, nums, total, HashMap()) return result } /* * solution:recursion+memorization (Top-Down); * if without memorization, Time complexity:O(2^n); * now with memorization, Time complexity:O(n*m), * where m is total of there different num we have, Space complexity:O(n); * */ private fun dfs(index: Int, sum: Int, nums: IntArray, total: Int, map: HashMap<String, Boolean>): Boolean { //set a key for map val key = "$index-$sum" if (map.containsKey(key)) { return map.get(key)!! } if (sum * 2 == total) { //got the result return true } if (sum > total / 2 || index >= nums.size) { return false } //not choice and choice, 2 situation val result = dfs(index + 1, sum, nums, total, map) || dfs(index + 1, sum + nums[index], nums, total, map) map.put(key, result) return result } }
标签:Subset,map,return,nums,sum,Partition,416,result,total 来源: https://www.cnblogs.com/johnnyzhao/p/13036630.html
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