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https://github.com/krahets/hello-algo.git
synced 2025-11-01 20:12:07 +08:00
Add python code of Heap and Graph to docs.
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@ -9,7 +9,7 @@ sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
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from include import *
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""" 基于邻接表实现的无向图类 """
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""" 基于邻接表实现的无向图类 """
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class GraphAdjList:
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# 邻接表,key: 顶点,value:该顶点的所有邻接结点
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adj_list = {}
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@ -8,6 +8,7 @@ import sys, os.path as osp
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sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
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from include import *
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""" 基于邻接矩阵实现的无向图类 """
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class GraphAdjMat:
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# 顶点列表,元素代表“顶点值”,索引代表“顶点索引”
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@ -75,7 +76,7 @@ class GraphAdjMat:
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self.adj_mat[i][j] = 0
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self.adj_mat[j][i] = 0
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# 打印邻接矩阵
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""" 打印邻接矩阵 """
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def print(self):
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print("顶点列表 =", self.vertices)
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print("邻接矩阵 =")
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@ -8,9 +8,9 @@ import sys, os.path as osp
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sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
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from include import *
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# 大顶堆
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""" 大顶堆 """
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class MaxHeap:
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# 使用列表而非数组,这样无需考虑扩容问题
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""" 构造方法 """
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def __init__(self, nums: List[int]):
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# 将列表元素原封不动添加进堆
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self.max_heap = nums
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@ -18,43 +18,43 @@ class MaxHeap:
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for i in range(self.parent(self.size() - 1), -1, -1):
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self.sift_down(i)
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# 获取左子结点索引
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""" 获取左子结点索引 """
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def left(self, i: int) -> int:
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return 2 * i + 1
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# 获取右子结点索引
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""" 获取右子结点索引 """
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def right(self, i: int) -> int:
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return 2 * i + 2
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# 获取父结点索引
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""" 获取父结点索引 """
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def parent(self, i: int) -> int:
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return (i - 1) // 2 # 向下整除
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# 交换元素
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""" 交换元素 """
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def swap(self, i: int, j: int):
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a, b = self.max_heap[i], self.max_heap[j]
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self.max_heap[i], self.max_heap[j] = b, a
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# 获取堆大小
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""" 获取堆大小 """
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def size(self) -> int:
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return len(self.max_heap)
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# 判断堆是否为空
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""" 判断堆是否为空 """
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def is_empty(self) -> bool:
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return self.size() == 0
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# 访问堆顶元素
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""" 访问堆顶元素 """
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def peek(self) -> int:
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return self.max_heap[0]
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# 元素入堆
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""" 元素入堆 """
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def push(self, val: int):
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# 添加结点
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self.max_heap.append(val)
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# 从底至顶堆化
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self.sift_up(self.size() - 1)
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# 从结点 i 开始,从底至顶堆化
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""" 从结点 i 开始,从底至顶堆化 """
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def sift_up(self, i: int):
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while True:
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# 获取结点 i 的父结点
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@ -67,7 +67,7 @@ class MaxHeap:
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# 循环向上堆化
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i = p
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# 元素出堆
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""" 元素出堆 """
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def poll(self) -> int:
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# 判空处理
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assert not self.is_empty()
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@ -80,7 +80,7 @@ class MaxHeap:
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# 返回堆顶元素
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return val
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# 从结点 i 开始,从顶至底堆化
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""" 从结点 i 开始,从顶至底堆化 """
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def sift_down(self, i: int):
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while True:
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# 判断结点 i, l, r 中值最大的结点,记为 ma
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@ -97,7 +97,7 @@ class MaxHeap:
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# 循环向下堆化
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i = ma
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# 打印堆(二叉树)
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""" 打印堆(二叉树) """
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def print(self):
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print_heap(self.max_heap)
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