Heap

A Sequence $\{a_n\}_{n=1}^N$ forms a heap if it satisfies $a_{\left\lfloor{j/2}\right\rfloor }\geq a_j$ for $1\leq\left\lfloor{j/2}\right\rfloor <j\leq N$, where $\left\lfloor{x}\right\rfloor$ is the Floor Function.

See also Heapsort