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CombinationSumII.java
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56 lines (51 loc) · 1.83 KB
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package algorithm.lc;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
/**
* 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 <= a
* ... , 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]
*
*/
public class CombinationSumII {
// DFS
public class Solution {
public ArrayList<ArrayList<Integer>> combinationSum2(int[] candidates, int target) {
// Start typing your Java solution below
// DO NOT write main() function
Set<ArrayList<Integer>> res = new HashSet<ArrayList<Integer>>();
int curIdx = 0;
ArrayList<Integer> cur = new ArrayList<Integer>();
int sum = 0;
Arrays.sort(candidates);
generate(candidates, target, res, curIdx, cur, sum);
return new ArrayList<ArrayList<Integer>>(res);
}
private void generate(int[] candidates, int target, Set<ArrayList<Integer>> res, int curIdx, ArrayList<Integer> cur, int sum) {
if (curIdx == candidates.length) {
if (sum == target) {
res.add(cur);
}
return;
}
int curVal = candidates[curIdx];
if (sum + curVal <= target) {
ArrayList<Integer> next = new ArrayList<Integer>(cur);
next.add(curVal);
generate(candidates, target, res, curIdx + 1, next, sum + curVal);
}
generate(candidates, target, res, curIdx + 1, cur, sum);
}
}
}