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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.
题目链接:https://leetcode.com/problems/partition-equal-subset-sum/
题目分析:sum必须是偶数,对sum/2,进行01背包dp
8ms,时间击败87.5%
class Solution {
public boolean canPartition(int[] nums) {
int sum = 0;
for (int i = 0; i < nums.length; i++) {
sum += nums[i];
}
if ((sum & 1) == 1) {
return false;
}
int target = sum >> 1;
boolean[] dp = new boolean[target + 1];
dp[0] = true;
for (int i = 0; i < nums.length; i++) {
for (int j = target; j >= nums[i]; j--) {
if (dp[j - nums[i]]) {
if (j == target) {
return true;
}
dp[j] = true;
}
}
}
return false;
}
}
本题最快的做法是sort完了DFS剪枝