0090-subsets-ii.ts

function subsetsWithDup(nums: number[]): number[][] {
    let res: number[][] = [];
    nums.sort();

    function backtrack(i: number, subset: number[]) {
        if (i == nums.length) {
            res.push(subset.slice());
            return;
        }

        subset.push(nums[i]);
        backtrack(i + 1, subset);

        subset.pop();

        while (i + 1 < nums.length && nums[i] == nums[i + 1]) {
            i += 1;
        }

        backtrack(i + 1, subset);
    }

    backtrack(0, []);

    return res;
}