"One Day together Leetcode" #78. Subsets

One Day together Leetcode

This series of articles has all been uploaded to my github address: Zeecoder ' s GitHub
You are welcome to follow my Sina Weibo, my Sina Weibo blog
Welcome reprint, Reprint please indicate the source

(i) Title

Given a set of distinct integers, nums, return all possible subsets.

Note:

• Elements in a subset must is in non-descending order.

• The solution set must not contain duplicate subsets.

For example,
If nums = [A/b], a solution is:

[
[3],
[1],
[2],
[A],
[1,3],
[2,3],
[+],
[]
]

(ii) Problem solving

The main idea: given a set of numbers, calculate all of its subsets

There are several points to note:

1. Subsets cannot be duplicated

2. The number in a subset needs to be arranged in a non-descending order

Problem solving: Consider using a bitwise operation to simulate all permutations and combinations. Take the number set size equal to 3 for example:

The full array of 3-bit binaries is: 000,001,010,011,100,101,111

With this all-in arrangement, the subset is selected for 1, and 0 is not selected. It's easy to get all the subsets

classSolution { Public: vector<vector<int>>Subsets ( vector<int>& Nums) {Longn =POW(2, Nums.size ());//number of digits to get the full rank maximum valueSort (Nums.begin (), Nums.end ());//Because the number of subsets needs to be arranged in a non-descending order, the set is sorted first         vector<vector<int>>Ret for(Longi =0; I < n; i++) { vector<int>Tempset; for(intj =0; J < Nums.size (); j + +) {if((I&GT;&GT;J) &1==1)//Determine if each bit is 1{Tempset.push_back (nums[j]);        }} ret.push_back (Tempset); }returnRet }};

"One Day together Leetcode" #78. Subsets