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.
public class Solution { /** * @param num: Given the candidate numbers * @param target: Given the target number * @return: All the combinations that sum to target */ public List<List<Integer>> combinationSum2(int[] num, int target) { List<List<Integer>> results = new ArrayList<>(); if (num == null || num.length == 0) { return results; } Arrays.sort(num); List<Integer> result = new ArrayList<>(); dfsHelper(num, target, 0, results, result); return results; } PRivate void dfsHelper(int[] num, int remainTarget, int index, List<List<Integer>> results, List<Integer> result) { if (remainTarget == 0) { results.add(new ArrayList<>(result)); } //不使用hash进行去重，if语句的作用是保证不跳跃着取相同的值，如 1,2',2''，不出现1,2'' for (int i = index; i < num.length; i++) { if (i != index && num[i] == num[i - 1]) { continue; } if (remainTarget < num[i]) { break; } result.add(num[i]); dfsHelper(num, remainTarget - num[i], i + 1, results, result); result.remove(result.size() - 1); } }}新闻热点
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