LeetCode -- Permutations

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public class Solution {
    public IList<IList<int>> Permute(int[] nums) {
       return Collect(nums.ToList());
}


private IList<IList<int>> Collect(IList<int> nums)
{
	if(nums.Count <= 1){
		return new List<IList<int>>(){new List<int>(nums)};
	}
	if(nums.Count == 2){
		return new List<IList<int>>(){new List<int>(){nums[0],nums[1]},new List<int>(){nums[1],nums[0]}};
	}
	var newSet = new List<IList<int>>();
	
	for(var i = 0;i < nums.Count; i++){
		// take out nums[i] and put at last for each sub set
		var x = nums[i];
		nums.RemoveAt(i);
		var subSet = Collect(nums);
		for(var k = 0;k < subSet.Count; k++){
			subSet[k].Add(x);
			newSet.Add(subSet[k]);
		}
		nums.Insert(i, x);
	}
	
	return newSet;
}


}

LeetCode -- Permutations

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原文地址：http://blog.csdn.net/lan_liang/article/details/48731289