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CombinationSum.cpp
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48 lines (42 loc) · 1.53 KB
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/**
Given a set of candidate numbers (C) and a target number (T), find all unique
combinations in C where the candidate numbers sums to T.
The same repeated number may be chosen from C unlimited number of times.
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 2,3,6,7 and target 7,
A solution set is:
[7]
[2, 2, 3]
*/
class Solution {
public:
void combinationSumUtil(vector<vector<int> >& ret, vector<int> combination,
vector<int>& candidates, int target,
int sum, int start) {
if (sum > target) return ;
if (sum == target) {
ret.push_back(combination);
return ;
}
for (int i = start; i < candidates.size(); ++i) {
sum += candidates[i];
combination.push_back(candidates[i]);
combinationSumUtil(ret, combination, candidates, target, sum, i);
sum -= candidates[i];
combination.pop_back();
}
}
vector<vector<int> > combinationSum(vector<int> &candidates, int target) {
vector<vector<int> > ret;
vector<int> combination;
int sum =0;
int start = 0;
std::sort(candidates.begin(), candidates.end());
combinationSumUtil(ret, combination, candidates, target, sum, start) ;
return ret;
}
};