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| class Solution {
public List<List<Integer>> combinationSum2(int[] candidates, int target) {
List<List<Integer>> res = new ArrayList<>();
Arrays.sort(candidates);
backtrack(candidates, target, new ArrayList<>(), res, 0);
return res;
}
public void backtrack(int[] candidates, int pathSum, List<Integer> path, List<List<Integer>> res, int start) {
if (pathSum == 0) {
res.add(new ArrayList<>(path)); // 找到一个组合，加入结果集
return;
} else if (pathSum < 0) { // 剪枝，如果 pathSum 小于 0，说明当前组合不合法，直接返回
return;
}
for (int i = start; i < candidates.length; i++) {
if (i > start && candidates[i] == candidates[i - 1]) { // 去重，跳过重复的元素
continue;
}
path.add(candidates[i]);
backtrack(candidates, pathSum - candidates[i], path, res, i + 1);
path.remove(path.size() - 1);
}
}
}
|