标签：code visit logs dup cti 开始 一个 class private
Given a collection of numbers that might contain duplicates, return all possible unique permutations. For example, [1,1,2] have the following unique permutations: [ [1,1,2], [1,2,1], [2,1,1] ]
从头开始且避免同级重复元素的出现,就用visited, 如果前一个没被访问则后一个不能被访问, 因为结果容器已经存在了
if (visited[i] == 1) { continue; } if (i > 0 && nums[i - 1] == nums[i] && visited[i - 1] == 0) { continue; } visited[i] = 1;
public List<List<Integer>> permuteUnique(int[] nums) {
List<List<Integer>> result = new ArrayList<List<Integer>>();
List<Integer> list = new ArrayList<Integer>();
if (nums.length == 0) {
result.add(list);
return result;
}
int[] visited = new int[nums.length] ;
for (int i = 0; i < nums.length; i++) {
visited[i] = 0;
}
Arrays.sort(nums);
helper(result, list, nums, visited);
return result;
}
private void helper(List<List<Integer>> result, List<Integer> list,
int[] nums, int[] visited) {
if (list.size() == nums.length ) {
result.add(new ArrayList<Integer>(list));
return;
}
for (int i = 0; i < nums.length; i++) {
if (visited[i] == 1) {
continue;
}
if (i > 0 && nums[i - 1] == nums[i] && visited[i - 1] == 0) {
continue;
}
visited[i] = 1;
list.add(nums[i]);
helper(result, list, nums, visited);
visited[i] = 0;
list.remove(list.size() - 1);
}
}
标签：code visit logs dup cti 开始 一个 class private
原文地址：http://www.cnblogs.com/apanda009/p/7230073.html
