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CombinationSumIi.java
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CombinationSumIi.java
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// Link: https://leetcode.com/problems/combination-sum-ii/
// DFS
// 1ms, 100%
class Solution {
public List<List<Integer>> combinationSum2(int[] candidates, int target) {
// Sort first for de-duplicating
Arrays.sort(candidates);
List<List<Integer>> ans = new ArrayList<>();
List<Integer> cur = new ArrayList<>();
dfs(candidates, target, 0, ans, cur);
return ans;
}
private void dfs(int[] candidates, int target, int startIdx, List<List<Integer>> ans, List<Integer> cur) {
if (target == 0) {
ans.add(new ArrayList<>(cur));
return;
}
for (int i = startIdx; i < candidates.length; ++i) {
if (candidates[i] <= target) {
cur.add(candidates[i]);
dfs(candidates, target - candidates[i], i + 1, ans, cur);
cur.remove(cur.size() - 1);
// skip the duplicates
for (; i + 1 < candidates.length && candidates[i] == candidates[i + 1]; ++i);
} else {
return;
}
}
}
}
/*
* Time complexity:
*
* Space complexity:
*
* Notes:
* Sort the array so that we can skip the duplicates easily.
*/