leetcode 416. 分割等和子集

https://leetcode-cn.com/problems/partition-equal-subset-sum/

0-1背包问题变形

class Solution {
public:
    bool canPartition(vector& nums) {
        int sum = 0;
        for (auto n : nums)
            sum += n;
        
        if (sum&0x1) return false;  //奇数不可能
        
        int n = nums.size();
        int target = sum>>1;
        bool dp[n][target+1]={};
        dp[0][0] = true;
        if (nums[0]<=target)
            dp[0][nums[0]] = true;
        
        for (int i = 1; i < n; ++i)
        {
            for (int j = 0; j <= target; ++j)
            {
                if (dp[i-1][j]) 
                {
                    dp[i][j] = true;
                    int t = j+nums[i];
                    if (t<=target)
                        dp[i][t] = true;
                }                                        
            }          
        }
        
        return dp[n-1][target];
    }
};

参考:

https://time.geekbang.org/column/article/74788