python---使用二叉堆实现的优先队列(列表)

哟，有实用价值

可以看到，加入是随机的，而吐出是顺序的。

# coding = utf-8

# 使用二叉堆实现的优先队列(列表)
class BinaryHeap:
    def __init__(self):
        self.heap_list = [0]
        self.current_size = 0

    def perc_up(self, i):
        while i // 2 > 0:
            if self.heap_list[i] < self.heap_list[i//2]:
                self.heap_list[i//2], self.heap_list[i] = \
                    self.heap_list[i], self.heap_list[i//2]
            i //= 2

    def insert(self, k):
        self.heap_list.append(k)
        self.current_size = self.current_size + 1
        self.perc_up(self.current_size)

    def min_child(self, i):
        if i * 2 + 1 > self.current_size:
            return i * 2
        else:
            if self.heap_list[i*2] < self.heap_list[i*2+1]:
                return i * 2
            else:
                return i * 2 + 1

    def perc_down(self, i):
        while (i*2) <= self.current_size:
            mc = self.min_child(i)
            if self.heap_list[i] > self.heap_list[mc]:
                self.heap_list[i], self.heap_list[mc] = \
                    self.heap_list[mc], self.heap_list[i]
            i = mc

    def del_min(self):
        ret_val = self.heap_list[1]
        self.heap_list[1] = self.heap_list[self.current_size]
        self.current_size = self.current_size - 1
        self.heap_list.pop()
        self.perc_down(1)
        return ret_val

    def build_heap(self, a_list):
        i = len(a_list) // 2
        self.current_size = len(a_list)
        self.heap_list = [0] + a_list[:]
        while i > 0:
            self.perc_down(i)
            i -= 1

bh = BinaryHeap()
bh.build_heap([9, 5, 6, 2, 3])
print(bh.del_min())
print(bh.del_min())
print(bh.del_min())
print(bh.del_min())
print(bh.del_min())

2
3
5
6
9