416.Partition Equal Subset Sum

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:

1. Each of the array element will not exceed 100.
2. 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.

public boolean canPartition(int[] nums) {
    int sum = 0;
    for (int num : nums)
        sum += num;
    if ((sum & 1) == 1)
        return false;
    sum = sum / 2;
    boolean[] dp = new boolean[sum + 1]; // dp表示，这个数是否是可达的
    dp[0] = true;
    for (int i = 0; i < nums.length; i++) {
        for (int j = sum; j >= nums[i]; j--)
            dp[j] = dp[j] || dp[j-nums[i]];
        if (dp[sum])
            return true;
    }
    return dp[sum];
}

和题目494解法一样