- Difficulty: Hard
- Tags: LeetCode, Hard, Math, Combinatorics, leetcode-2927, O(1), 🔒, Stars and Bars, Principle of Inclusion and Exclusion
Problem
You are given two positive integers n
and limit
.
Return the total number of ways to distribute n
candies among 3
children such that no child gets more than limit
candies.
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Example 1:
Input: n = 5, limit = 2 Output: 3 Explanation: There are 3 ways to distribute 5 candies such that no child gets more than 2 candies: (1, 2, 2), (2, 1, 2) and (2, 2, 1).
Example 2:
Input: n = 3, limit = 3 Output: 10 Explanation: There are 10 ways to distribute 3 candies such that no child gets more than 3 candies: (0, 0, 3), (0, 1, 2), (0, 2, 1), (0, 3, 0), (1, 0, 2), (1, 1, 1), (1, 2, 0), (2, 0, 1), (2, 1, 0) and (3, 0, 0).
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Constraints:
1 <= n <= 108
1 <= limit <= 108