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LeetCode46.java
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65 lines (60 loc) · 1.81 KB
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package problems;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Deque;
import java.util.List;
public class LeetCode46 {
public List<List<Integer>> permute(int[] nums) {
int length=nums.length;
List<List<Integer>> ans=new ArrayList<>();
if(length==0){
return ans;
}
Deque<Integer> path = new ArrayDeque<>();
boolean used[]=new boolean[length];
dfs(nums,length,0,path,used,ans);
return ans;
}
// 深搜
private void dfs(int[] nums, int length, int depth, Deque<Integer> path, boolean[] used, List<List<Integer>> ans) {
if(depth==length){
ans.add(new ArrayList<>(path));
return;
}
for(int i=0;i<length;i++){
if(used[i]){
continue;
}
path.addLast(nums[i]);
used[i]=true;
dfs(nums,length,depth+1,path,used,ans);
path.removeLast();
used[i]=false;
}
}
}
class LeetCode46_1{
public List<List<Integer>> permute(int[] nums) {
List<List<Integer>> ret = new ArrayList<>();
Deque<Integer> path = new ArrayDeque<>();
int length = nums.length;
boolean[] used = new boolean[length];
dfs(nums, used, length, path, ret);
return ret;
}
void dfs(int[] nums, boolean[] used, int length, Deque<Integer> path, List<List<Integer>> ret){
if(path.size() == length){
ret.add(new ArrayList<>(path));
return;
}
for (int i = 0; i < length; i++) {
if(!used[i]){
used[i] = true;
path.add(nums[i]);
dfs(nums, used, length, path, ret);
path.removeLast();
used[i] = false;
}
}
}
}