满足最小堆定义的是()
{21, 25, 55, 23, 51, 63}
{21, 51, 55, 63, 25, 23}
{21, 63, 55, 25, 51, 23}
{21, 51, 23, 63, 55, 25}
题目考查最小堆。
21<51,23;51<63,55;23<25。满足定义。