In this post, we are going to solve the Combination Sum Leetcode Solution problem of Leetcode. This Leetcode problem is done in many programming languages like C++, Java, and Python.
Problem
Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. You may return the combinations in any order.
The same number may be chosen from candidates an unlimited number of times. Two combinations are unique if the frequency of at least one of the chosen numbers is different.
The test cases are generated such that the number of unique combinations that sum up to target is less than 150 combinations for the given input.
Example 1:
Input: candidates = [2,3,6,7], target = 7 Output: [[2,2,3],[7]] Explanation: 2 and 3 are candidates, and 2 + 2 + 3 = 7. Note that 2 can be used multiple times. 7 is a candidate, and 7 = 7. These are the only two combinations.
Example 2:
Input: candidates = [2,3,5], target = 8 Output: [[2,2,2,2],[2,3,3],[3,5]]
Example 3:
Input: candidates = [2], target = 1 Output: []
Constraints:
1 <= candidates.length <= 302 <= candidates[i] <= 40- All elements of
candidatesare distinct. 1 <= target <= 500
Now, let’s see the leetcode solution of Combination Sum Leetcode Solution.
Combination Sum Leetcode Solution in Python
class Solution:
def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
ans = []
def dfs(s: int, target: int, path: List[int]) -> None:
if target < 0:
return
if target == 0:
ans.append(path.clone())
return
for i in range(s, len(candidates)):
path.append(candidates[i])
dfs(i, target - candidates[i], path)
path.pop()
candidates.sort()
dfs(0, target, [])
return ans
Combination Sum Leetcode Solution in CPP
class Solution {
public:
vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
vector<vector<int>> ans;
sort(begin(candidates), end(candidates));
dfs(candidates, 0, target, {}, ans);
return ans;
}
private:
void dfs(const vector<int>& A, int s, int target, vector<int>&& path,
vector<vector<int>>& ans) {
if (target < 0)
return;
if (target == 0) {
ans.push_back(path);
return;
}
for (int i = s; i < A.size(); ++i) {
path.push_back(A[i]);
dfs(A, i, target - A[i], move(path), ans);
path.pop_back();
}
}
};
Combination Sum Leetcode Solution in Java
class Solution {
public List<List<Integer>> combinationSum(int[] candidates, int target) {
List<List<Integer>> ans = new ArrayList<>();
Arrays.sort(candidates);
dfs(0, candidates, target, new ArrayList<>(), ans);
return ans;
}
private void dfs(int s, int[] candidates, int target, List<Integer> path,
List<List<Integer>> ans) {
if (target < 0)
return;
if (target == 0) {
ans.add(new ArrayList<>(path));
return;
}
for (int i = s; i < candidates.length; ++i) {
path.add(candidates[i]);
dfs(i, candidates, target - candidates[i], path, ans);
path.remove(path.size() - 1);
}
}
}
Note: This problem Combination Sum is generated by Leetcode but the solution is provided by Chase2learn This tutorial is only for Educational and Learning purposes.
NEXT: Combination Sum II
