时间复杂度（O( n^2)），思想，bfs广度优先+set

class Solution {
public:
    bool canPartition(vector<int>& nums) {
        int sum=0;
        vector<int> vec(101,0);
        for(int k=0;k<nums.size();++k) sum+=nums[k];
        if(sum%2) return false;
        set<int> hashSet;
        hashSet.insert(0);
        for(int i=0;i<nums.size();++i){
            vector<int> vec;
            for (set<int>::iterator iterCur = hashSet.begin(); iterCur != hashSet.end(); ++iterCur)
                vec.push_back(*iterCur+nums[i]);
            for(auto v:vec) hashSet.insert(v);
        }
        return hashSet.count(sum/2)<=0?false:true;
    }
};

时间复杂度（O( n^2)），思想，bfs广度优先

class Solution {
public:
    bool canPartition(vector<int>& nums) {
        int sum=0;
        for(int k=0;k<nums.size();++k) sum+=nums[k];
        if(sum%2) return false;
        sum=sum/2;
        vector<int> vecall;
        vecall.push_back(0);
        vector<bool> vec_set(sum+1,false);
        vec_set[0]=true;
        for(int i=0;i<nums.size();++i){
            vector<int> vec;
            for(auto v1:vecall){
                int curr = v1+nums[i];
                if(curr==sum)return true;
                else if(curr>sum||vec_set[curr])continue;
                vec_set[curr]=true;
                vec.push_back(curr);
            }
            for(auto v:vec)    vecall.push_back(v);
        }
        return false;
    }
};