Leetcode 1692. Count Ways to Distribute Candies

Count the number of distinct ways to distribute candies to recipients under given constraints (such as limits per type or per child, and indistinguishable vs. distinguishable items), returning the result modulo a large prime. The hard part is efficient combinatorial counting for large inputs, typically requiring DP, inclusion–exclusion or precomputed factorials/inverse factorials to avoid brute-force enumeration.