LeetCode 698 Partition to K Equal Sum Subsets - Problem Statement

Given an array nums and integer $k$, determine if the array can be divided into $k$ non-empty subsets with equal sum. Example: nums $= [4, 3, 2, 3, 5, 2, 1]$, $k = 4$. Total $= 20$, target per subset $= 5$. Partition: $\{5\}, \{4, 1\}, \{3, 2\}, \{3, 2\}$. Return true.

This needs bitmask DP because you must track exactly which elements have been used. Standard sum-based DP can't distinguish different groupings that reach the same partial sum.