40. Combination Sum II

Alen Alex · February 9, 2026

LeetCode Link: 40. Combination Sum II
Language: C#

Problem Statement

Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sum to target.

Each number in candidates may only be used once in the combination.

Note: The solution set must not contain duplicate combinations.

Example 1:

Input: candidates = [10,1,2,7,6,1,5], target = 8
Output:
[
[1,1,6],
[1,2,5],
[1,7],
[2,6]
]

Example 2:

Input: candidates = [2,5,2,1,2], target = 5
Output:
[
[1,2,2],
[5]
]

Constraints:

  • 1 <= candidates.length <= 100
  • 1 <= candidates[i] <= 50
  • 1 <= target <= 30

Solution

public class Solution 
{
    public bool IsIdealPermutation(int[] nums) 
    {
        var max = -1;

        for (int i=0; i<nums.Length - 2; i++)
        {
            max = Math.Max(max, nums[i]);

            if (max > nums[i + 2])
            {
                return false;
            }
        }

        return true;
    }
}

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