1282. Group the People Given the Group Size They Belong To

There are n people that are split into some unknown number of groups. Each person is labeled with a unique ID from 0 to n - 1.

You are given an integer array groupSizes, where groupSizes[i] is the size of the group that person i is in. For example, if groupSizes[1] = 3, then person 1 must be in a group of size 3.

Return a list of groups such that each person i is in a group of size groupSizes[i].

Each person should appear in exactly one group, and every person must be in a group. If there are multiple answers, return any of them. It is guaranteed that there will be at least one valid solution for the given input.

 

Example 1:

Input: groupSizes = [3,3,3,3,3,1,3]
Output: [[5],[0,1,2],[3,4,6]]
Explanation: 
The first group is [5]. The size is 1, and groupSizes[5] = 1.
The second group is [0,1,2]. The size is 3, and groupSizes[0] = groupSizes[1] = groupSizes[2] = 3.
The third group is [3,4,6]. The size is 3, and groupSizes[3] = groupSizes[4] = groupSizes[6] = 3.
Other possible solutions are [[2,1,6],[5],[0,4,3]] and [[5],[0,6,2],[4,3,1]].

Example 2:

Input: groupSizes = [2,1,3,3,3,2]
Output: [[1],[0,5],[2,3,4]]

 

Constraints:

  • groupSizes.length == n
  • 1 <= n <= 500
  • 1 <= groupSizes[i] <= n

Rust Solution

struct Solution;

type Person = (i32, usize);

impl Solution {
    fn group_the_people(group_sizes: Vec<i32>) -> Vec<Vec<i32>> {
        let mut people: Vec<Person> = vec![];
        let mut res: Vec<Vec<i32>> = vec![];
        for (id, &group_size) in group_sizes.iter().enumerate() {
            people.push((group_size, id))
        }
        people.sort_unstable();
        let mut group: Vec<i32> = vec![];
        for p in people {
            group.push(p.1 as i32);
            if group.len() == p.0 as usize {
                res.push(group);
                group = vec![];
            }
        }
        res
    }
}

#[test]
fn test() {
    let group_sizes = vec![3, 3, 3, 3, 3, 1, 3];
    let res = vec_vec_i32![[5], [0, 1, 2], [3, 4, 6]];
    assert_eq!(Solution::group_the_people(group_sizes), res);
    let group_sizes = vec![2, 1, 3, 3, 3, 2];
    let res = vec_vec_i32![[1], [0, 5], [2, 3, 4]];
    assert_eq!(Solution::group_the_people(group_sizes), res);
}

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