| # Array-Based Priority Queue | |
| ## Problem Description | |
| Build, update, pop, and sort an integer heap represented by an array. | |
| ## Required Function Contracts | |
| This task specifies a multi-function API. Provide a separate `Require` / `Ensure` contract on **each** of the following functions in `solution.c`: | |
| - `push` | |
| - `build` | |
| - `pop` | |
| - `heap_sort` | |
| Every function listed above is a specification target, including functions called internally by other operations. A contract only on the final or highest-level operation is incomplete. Keep the existing C signatures and bodies unchanged; no loop annotations are requested. | |
| ## Input | |
| The functions receive the array representation, its logical size or capacity, and the operation-specific values described by their C signatures. | |
| ## Output | |
| Each operation returns or updates the represented data structure according to its interface contract. | |
| ## Constraints | |
| All indices, sizes, capacities, and stored values satisfy the bounds stated by the corresponding function contract. | |
| ## Source | |
| Classical data-structure implementation reconstructed from the verified C artifact. | |