(78)
public List<List<Integer>> subsets(int[] nums) {
List<List<Integer>> list = new ArrayList<>();
Arrays.sort(nums);
backtrack(list, new ArrayList<>(), nums, 0);
return list;
}
private void backtrack(List<List<Integer>> list , List<Integer> tempList, int [] nums, int start){
for(Integer n: tempList){
System.out.print(n + " ");
}
System.out.println();
list.add(new ArrayList<>(tempList));
for(int i = start; i < nums.length; i++){
tempList.add(nums[i]);
backtrack(list, tempList, nums, i + 1);
tempList.remove(tempList.size() - 1);
}
}
(90)
public List<List<Integer>> subsetsWithDup(int[] nums){
List<List<Integer>> ans = new ArrayList<>();
Arrays.sort(nums);
dfs(ans, new ArrayList<>(), nums, 0);
return ans;
}
public void dfs(List<List<Integer>> set, List<Integer> tempList, int[] nums, int start){
set.add(new ArrayList<>(tempList));
for(int i = start; i < nums.length; i++){
if(i > start && nums[i] == nums[i - 1]) continue;
tempList.add(nums[i]);
dfs(set, tempList, nums, i + 1);
tempList.remove(tempList.size() - 1);
}
}
(46)
public List<List<Integer>> permute(int[] nums) {
List<List<Integer>> list = new ArrayList<>();
// Arrays.sort(nums); // not necessary
backtrack(list, new ArrayList<>(), nums);
return list;
}
private void backtrack(List<List<Integer>> list, List<Integer> tempList, int [] nums){
if(tempList.size() == nums.length){
list.add(new ArrayList<>(tempList));
} else{
for(int i = 0; i < nums.length; i++){
if(tempList.contains(nums[i])) continue; // element already exists, skip
tempList.add(nums[i]);
backtrack(list, tempList, nums);
tempList.remove(tempList.size() - 1);
}
}
}
47
public List<List<Integer>> permuteUnique(int[] nums) {
List<List<Integer>> list = new ArrayList<>();
Arrays.sort(nums);
backtrack(list, new ArrayList<>(), nums, new boolean[nums.length]);
return list;
}
private void backtrack(List<List<Integer>> list, List<Integer> tempList, int [] nums, boolean [] used){
if(tempList.size() == nums.length){
list.add(new ArrayList<>(tempList));
} else{
for(int i = 0; i < nums.length; i++){
if(used[i] || i > 0 && nums[i] == nums[i-1] && !used[i - 1]) continue;
used[i] = true;
tempList.add(nums[i]);
backtrack(list, tempList, nums, used);
used[i] = false;
tempList.remove(tempList.size() - 1);
}
}
}
(39)
public List<List<Integer>> combinationSum(int[] candidate, int target) {
List<List<Integer>> ans = new ArrayList<>();
backTrack(ans, new ArrayList<>(), candidate, target, 0, 0);
return ans;
}
public void backTrack(List<List<Integer>> ans, List<Integer> tempList, int[] candidate, int target, int sum, int start) {
if(sum > target) return;
if (sum == target) ans.add(new ArrayList<>(tempList));
for (int i = start; i < candidate.length; i++) {
tempList.add(candidate[i]);
backTrack(ans, tempList, candidate, target, sum + candidate[i], i);
tempList.remove(tempList.size() - 1);
}
}
(40)