Array Binary Heap

Min-heap over a fixed int array: ``c typedef struct { int a[64]; size_t n; } heap_t; void heap_push(heap_t *h, int v); int heap_pop(heap_t *h); /* returns min; caller ensures n>0 */ int heap_min(const heap_t *h); `` push appends and sifts up; pop swaps the root with the last, shrinks, sifts down.