标签：exp for elements tco turn range tar bool span
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:
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.
本题用DP来解。DP[i]表示是不是存在一个subset使得sum等于i.
1 class Solution(object): 2 def canPartition(self, nums): 3 """ 4 :type nums: List[int] 5 :rtype: bool 6 """ 7 s = sum(nums) 8 9 if s % 2 == 1: return False 10 target = s/2 11 dp = [False]*(target+1) 12 dp[0] = True 13 14 for i in range(len(nums)): 15 for j in range(target, nums[i] - 1, -1): 16 dp[j] = dp[j] or dp[j - nums[i]] 17 18 return dp[target]
用类似的方法还可以解决另外一个问题：给定一个list of positive integers和一个target. 是否存在一个subset使得sum(subset) = target?
def subsetSum(nums, target): s = sum(nums) if s < target: return False dp = [False] * (target + 1) dp[0] = True for i in range(len(nums)): for j in range(target, nums[i] - 1, -1): dp[j] = dp[j] or dp[j - nums[i]] return dp[target]
Leetcode 416. Partition Equal Subset Sum
标签：exp for elements tco turn range tar bool span
原文地址：http://www.cnblogs.com/lettuan/p/6127905.html
