javascript-data-structures-and-algorithms/src/backtracking/subsets/subsets.js at master · evgenirusev/javascript-data-structures-and-algorithms · GitHub

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/**
 * Iterative approach
 * Time complexity - O(N * 2N)
 * Space complexity - O(N * 2N)
 * https://leetcode.com/problems/subsets
 * @param {number[]} nums
 * @return {number[][]}
 */
function subsets(nums) {
    let output = [];
    let n = 0;
    let k = 0;

    function backtrack(first, curr, nums) {
        if (curr.length === k) {
            output.push([...curr]);
            return;
        }

        for (let i = first; i < n; ++i) {
            curr.push(nums[i]);
            backtrack(i + 1, curr, nums);
            curr.pop();
        }
      }

    n = nums.length;

    for (k = 0; k < n + 1; ++k)
        backtrack(0, [], nums);

    return output;
}

// Non-iterative approach:
// function subsets(nums) {
//     const res = [];
//     const subset = [];

//     function dfs(i) {
//         if (i >= nums.length) {
//             res.push([...subset]);
//             return;
//         }

//         subset.push(nums[i]);
//         dfs(i + 1);

//         subset.pop();
//         dfs(i + 1);
//     }

//     dfs(0);
//     return res;
// }

/*
* Cascading solution
* Time complexity - O(N * 2N)
* Space complexity - O(N * 2N)
*/
// function subsets(nums) {
//     let result = [[]];

//     nums.forEach(n => {
//         let newSubsets = [];
//         result.forEach(subset => {
//             newSubsets.push([...subset, n]);
//         });

//         result = [...result, ...newSubsets];
//     });

//     return result;
// }

module.exports = subsets;