LeetCode - Permutations (Java)

For example, [1,2,3] have the following permutations: [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. Java Solution 1 We can get all permutations by the following steps: [1] [2, 1] [1, 2] [3, 2, 1] [2, 3, 1] [2, 1, 3] [3, 1, 2] [1, 3, 2] [1, 2, 3] Loop through the array, in each iteration, a new number is added to different locations of results of previous iteration. Start from an empty List. public ArrayList> permute(int[] num) { ArrayList> result = new ArrayList>();   //start from an empty list result.

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