In this guide, you will get 377. Combination Sum IV LeetCode Solution with the best time and space complexity. The solution to Combination Sum IV problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.
Given an array of distinct integers nums and a target integer target, return the number of possible combinations that add up to target.
The test cases are generated so that the answer can fit in a 32-bit integer.
Example 1:
Input: nums = [1,2,3], target = 4
Output: 7
Explanation:
The possible combination ways are:
(1, 1, 1, 1)
(1, 1, 2)
(1, 2, 1)
(1, 3)
(2, 1, 1)
(2, 2)
(3, 1)
Note that different sequences are counted as different combinations.
Example 2:
Input: nums = [9], target = 3
Output: 0
Constraints:
1 <= nums.length <= 200
1 <= nums[i] <= 1000
All the elements of nums are unique.
1 <= target <= 1000
Follow up: What if negative numbers are allowed in the given array? How does it change the problem? What limitation we need to add to the question to allow negative numbers?
Complexity Analysis
Time Complexity: O(|\texttt{coins}| \cdot \texttt{target})
Space Complexity: O(\texttt{target})
377. Combination Sum IV LeetCode Solution in C++
class Solution {
public:
int combinationSum4(vector<int>& nums, int target) {
vector<unsigned long> dp(target + 1);
dp[0] = 1;
for (int i = 1; i <= target; ++i)
for (const int num : nums)
if (i >= num)
dp[i] += dp[i - num];
return dp[target];
}
}; /* code provided by PROGIEZ */
377. Combination Sum IV LeetCode Solution in Java
class Solution {
public int combinationSum4(int[] nums, int target) {
// dp[i] := the number of combinations that add up to i
int[] dp = new int[target + 1];
dp[0] = 1;
for (int i = 0; i <= target; ++i)
for (final int num : nums)
if (i >= num)
dp[i] += dp[i - num];
return dp[target];
}
} // code provided by PROGIEZ
377. Combination Sum IV LeetCode Solution in Python
class Solution:
def combinationSum4(self, nums: list[int], target: int) -> int:
dp = [1] + [-1] * target
def dfs(target: int) -> int:
if target < 0:
return 0
if dp[target] != -1:
return dp[target]
dp[target] = sum(dfs(target - num) for num in nums)
return dp[target]
return dfs(target) # code by PROGIEZ
