LeetCode 39. Combination Sum

​​题目​​

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struct Node
{
    vector<int> a;
    int sum;
    int index;
    Node(){}
    Node(int index,int sum,vector<int> a)
    {
        this->index = index;
        this->sum = sum;
        this->a = a;
    }
    
};

class Solution {
public:
    queue<Node> q;  
    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
        
        vector<vector<int>> ans;
        for(int i=0;i<candidates.size();i++)
        {
            vector<int> a;
            a.push_back(candidates[i]);
            q.push(Node(i,candidates[i],a));
        }
        
        while(!q.empty())
        {
            Node term = q.front();
            q.pop();
            
            if(term.sum==target)
            {
                ans.push_back(term.a);
                continue;
            }
            
            for(int i=term.index;i<candidates.size();i++)
            {
                if(term.sum+candidates[i]>target)
                    continue;
                else if(term.sum+candidates[i]==target)
                {
                     vector<int> x = term.a;
                    x.push_back(candidates[i]);
                    ans.push_back(x);
                }
                else
                {
                    vector<int> x = term.a;
                    x.push_back(candidates[i]);
                    q.push(Node(i,term.sum+candidates[i],x));
                }
            }
        }
        return ans;
    }
};