Combination Sum II

Author: Shikha-code36

Backtracking/40-Combination-Sum-II.py

@@ -0,0 +1,44 @@
+'''Leetcode- https://leetcode.com/problems/combination-sum-ii/'''
+'''
+Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sum to target.
+
+Each number in candidates may only be used once in the combination.
+
+Note: The solution set must not contain duplicate combinations.
+
+Example 1:
+
+Input: candidates = [10,1,2,7,6,1,5], target = 8
+Output: 
+[
+[1,1,6],
+[1,2,5],
+[1,7],
+[2,6]
+]
+'''
+
+
+def combinationSum2(candidates, target):
+    candidates.sort()
+    res = []
+
+    def backtrack(cur, pos, target):
+        if target == 0:
+            res.append(cur.copy())
+        if target <= 0:
+            return
+        prev = -1
+        for i in range(pos, len(candidates)):
+            if candidates[i] == prev:
+                continue
+            cur.append(candidates[i])
+            backtrack(cur, i+1, target-candidates[i])
+            cur.pop()
+            prev = candidates[i]
+
+    backtrack([], 0, target)
+    return res
+
+#T:O(2^n)
+#S:O(n)

README.md

@@ -14,4 +14,6 @@ Check the notes for the explaination - [Notes](https://stingy-shallot-4ea.notion
     - [x] [Permutations II](Backtracking/47-Permutations-II.py)
     - [x] [Combinations](Backtracking/77-Combinations.py)
     - [x] [Combination Sum](Backtracking/39-Combination-Sum.py)
+    - [x] [Combination Sum II](Backtracking/40-Combination-Sum-II.py)
+