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RSS订阅原创 《算法导论》-最长公共子序列（Python）
import numpy as npdef lcs_length(X, Y): m = len(X) n = len(Y) b = np.zeros((m+1, n+1)) b = b.astype('str') c = np.zeros((m+1, n+1)) for i in range(1, m+1): for j i...
2019-10-11 16:41:23
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原创 《算法导论》-矩阵链乘法（Python）
def memorized_cut_rod(p, n): r = [] for i in range(n+1): r.append(-float('inf')) return memoized_cut_rod_aux(p, n, r)def memoized_cut_rod_aux(p, n, r): if r[n] >= 0: ...
2019-10-08 15:26:09
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原创 《算法导论》-钢条切割（Python）
def memorized_cut_rod(p, n): r = [] for i in range(n+1): r.append(-float('inf')) return memoized_cut_rod_aux(p, n, r)def memoized_cut_rod_aux(p, n, r): if r[n] >= 0: ...
2019-10-07 16:43:33
303
原创 《算法导论》-计数排序（Python）
import numpy as npMAX = 20A = list(np.random.randint(MAX, size=16))B = A.copy()C = []for i in range(MAX+1): C.append(0)for j in range(len(A)): C[A[j]] += 1for m in range(1, MAX+1):...
2019-10-06 17:12:05
116
原创 《算法导论》-快速排序（Python）
import numpy as npdef partition(A, p, r): x = A[r] i = p - 1 for j in range(p, r): if A[j] <= x: i += 1 t = A[i] A[i] = A[j] ...
2019-08-29 21:04:32
130
原创 《算法导论》-优先队列（Python）
import numpy as npdef parent(i): return int((i-1)/2)def left(i): return 2 * i + 1def right(i): return 2 * (i + 1)def max_heapify(A, i): l = left(i) r = right(i) if...
2019-08-22 19:11:08
126
原创 《算法导论》-堆排序
import numpy as npdef parent(i): return int((i-1)/2)def left(i): return 2 * i + 1def right(i): return 2 * (i + 1)def max_heapify(A, i): l = left(i) r = right(i) if ...
2019-08-20 21:19:40
71
原创 《算法导论》-最大子数组
分治思想的求解代码：import numpy as npdef find_max_crossing_subarray(A, low, mid, high): left_sum = float('-inf') sum = 0 for i in range(mid, low-1, -1): sum += A[i] if sum >...
2019-08-14 20:23:32
167
原创 《算法导论》-归并排序
import numpy as npdef merge(A, p, q, r): n1 = q - p + 1 n2 = r - q L = A[p: p+n1] R = A[q+1: q+n2+1] i = 0 j = 0 for k in range(p, r+1): if L[i] <= R[j]: ...
2019-08-14 20:20:35
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原创 《西瓜书》-决策树
from sklearn.tree import DecisionTreeClassifierfrom sklearn.model_selection import train_test_splitfrom sklearn.preprocessing import LabelEncoderimport pandas as pdimport iodata_str = output = i...
2019-07-24 11:37:06
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原创 《西瓜书》-计算信息增益和基尼指数
import numpy as npimport pandas as pdimport matplotlib.pyplot as pltimport iodata_str = output = io.StringIO('''编号,色泽,根蒂,敲声,纹理,脐部,触感,密度,含糖率,好瓜1,青绿,蜷缩,浊响,清晰,凹陷,硬滑,0.697,0.46,是 2,乌黑,蜷缩,沉闷,清晰,凹陷...
2019-07-24 11:34:39
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