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Combination Sum II

2024-07-06 09:43:28   221人阅读

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

Each number in C may only be used once in the combination.

Note:

  • All numbers (including target) will be positive integers.
  • Elements in a combination (a1, a2, … , ak) must be in non-descending order. (ie, a1 ≤ a2 ≤ … ≤ ak).
  • The solution set must not contain duplicate combinations.

For example, given candidate set 10,1,2,7,6,1,5 and target 8, 
A solution set is: 
[1, 7] 
[1, 2, 5] 
[2, 6] 
[1, 1, 6] 

struct Node
{
  int key;
  int cnt;
};
class Solution {
private:
    vector<Node> v;
    vector<Node> data;
    vector<vector<int> > result;
    int len;
    
    void generate(int vdep,int index,int target)
    {
        if(target<0) return;
        if(target==0)
        {
            vector<int> re;
            for(int i=0;i<vdep;i++)
                for(int j=0;j<v[i].cnt;j++)
                    re.push_back(v[i].key);
            result.push_back(re);
            return;
        }
        for(int i=index;i<len;i++)
        {
            for(int j=1;j<=data[i].cnt;j++)
            {
                v[vdep].key=data[i].key;
                v[vdep].cnt=j;
                generate(vdep+1,i+1,target-v[vdep].key*j);
            }
        }
    }
public:
    vector<vector<int> > combinationSum2(vector<int> &num, int target) 
    {
        sort(num.begin(),num.end());
        //group
        int old=0;
        Node node;
        for(int i=0;i<num.size();i++)
        {
            if(num[i]==old) data[data.size()-1].cnt++;
            else
            {
                node.key=num[i];
                old=node.key;
                node.cnt=1;
                data.push_back(node);
            }
        }
        for(int i=0;i<num.size();i++)
            v.push_back(node);
                
        result.clear();
        
        len=data.size();
        
        generate(0,0,target);
        return result;
    }
}; 


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