Python手撕常用模版
标准输出
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| a = 10
print(a)
print("Hello" + ", " + "World!")
print("Hello", "World!", sep=", ")
s = "abc"
print(s, a)
print(f"{s} {a}")
print(f"{s} {a}", end = "")
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标准输入（ACM模式）
- 一般读入（stdin/input）
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| import sys
for line in sys.stdin:
a = line.split()
print(int(a[0])+int(a[1]))
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while True:
try:
a=int(input().split(" ")[0])
b=int(input().split(" ")[-1])
print(a+b)
except:
break
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- 读取多行输入且第一行为行数(即固定行数)
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| if __name__ == '__main__':
n = input()
for _ in range(n)
print(list(map(int, input().split())))
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- 读取多行输入但不知有多少行(以读入空行且是空字符串结束)
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| if __name__ == '__main__':
arr = []
for line in iter(input,''):
arr.append(line.split())
print(arr)
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- 读取多行输入但不知有多少行(以读入空行结束)
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| if __name__ == '__main__':
try:
arr = []
while True:
str_input = input().strip()
if str_input == '':
break
arr.append(str_input.split())
print(arr)
except:
pass
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列表List
- 初始化
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nums = []
nums = [1, 3, 5]
n = 10
nums = [0] * n
m, n = 3, 4
matrix = [[1] * n for _ in range(m)]
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- 常见方法
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| lst = [0] * 10
print(len(lst) == 0)
print(len(lst))
lst.append(4)
lst.pop()
lst.pop([index])
lst.insert(i, x)
lst.extend(lst1)
lst.remove(2)
lst.sort()
lst.reverse()
lst[1] = 20
lst[-1]表示最后一个数
for i in range(0, -10, -1)
for i in reversed(range(len(lst)-1))
lst = ["a", "b", "c"]
for i, v in enumerate(lst):
print(i, v)
date = "2019-8-15"
Y, M, D = map(int, date.split('-'))
lst1=sorted(lst)
lst2=sorted(lst,reverse=True)
l1 = [(1,2), (0,1), (3,10)]
l2 = sorted(l1, key=lambda x: x[0])
lst = [i*j for i in range(1,10)]
add = lambda a, b: a + b
x = [1, 2, 3]
y = [4, 5, 6]
zipped = zip(x, y)
list(zipped)
maxnums = max(maxnums, tmp)
lst_copy = lst.copy()
import copy
deep_copy = copy.deepcopy(lst)
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多维列表
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| ls = []
ls_T = list(map(list, zip(*ls)))
if 元素 in ls_T[0]:
j = ls_T[0].index(元素)
A = [[1,2,3],[4,5,6],[7,8,9]]
print(len(A))
print(len(A[0]))
B = [[A[j][i] for j in range(len(A))] for i in range(len(A[0]))]
print(B)
DIRS = [[0, 1], [1, 0], [0, -1], [-1, 0]]
di=0
nx, ny = x + DIRS[di][0], y + DIRS[di][1]
DIRS = [(0, 1), (1, 0), (0, -1), (-1, 0)]
for dx,dy in DIRS:
nx,ny = x+ dx, y + dy
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字符串String
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| ord('a')
chr(100)
' spacious '.strip()
'1,2,3'.split(',')
'1,2,3'.split(',', maxsplit=1)
str1 = '12345'
list1 = list(str1)
print(list1)
str3 = 'this is string example'
list3 = str3.split('i', 1)
print(list3)
list1 = ['1', '2', '3', '4', '5']
str1 = "".join(list1)
list3 = ['www', 'baidu', 'com']
str3 = ".".join(list3)
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双端队列Deque
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| from collections import deque
lst = deque([1, 2, 3, 4, 5])
print(len(lst) == 0)
print(len(lst))
lst.appendleft(0)
lst.append(6)
print(lst[0], lst[-1])
lst.popleft()
lst.pop()
lst.insert(2, 99)
del lst[1]
for val in lst:
print(val, end=" ")
print()
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队列Queue
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| from collections import deque
q = deque()
q.append(10)
q.append(20)
q.append(30)
print(len(q) == 0)
print(len(q))
print(q[0])
q.popleft()
print(q[0])
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栈Stack
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s = []
s.append(10)
s.append(20)
s.append(30)
print(len(s) == 0)
print(len(s))
print(s[-1])
s.pop()
print(s[-1])
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字典Dict
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hashmap = {1: "one", 2: "two", 3: "three"}
print(len(hashmap) == 0)
print(len(hashmap))
if 2 in hashmap:
print(f"Key 2 -> {hashmap[2]}")
else:
print("Key 2 not found.")
print(hashmap.get(4))
hashmap[4] = "four"
print(hashmap[4])
del hashmap[3]
if 3 in hashmap:
print(f"Key 3 -> {hashmap[3]}")
else:
print("Key 3 not found.")
for k, v in hashmap.items():
print(f"{k} -> {v}")
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集合Set
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hashset = {1, 2, 3, 4}
print(len(hashset) == 0)
print(len(hashset))
if 3 in hashset:
print("Element 3 found.")
else:
print("Element 3 not found.")
hashset.add(5)
hashset.discard(2)
if 2 in hashset:
print("Element 2 found.")
else:
print("Element 2 not found.")
for element in hashset:
print(element)
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计数器Counter
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| from collections import Counter
list1 = ["a", "a", "a", "b", "c", "c", "f", "g", "g", "g", "f"]
dic = Counter(list1)
print(dic)
print(dict(dic))
print(dic.items())
print(dic.keys())
print(dic.values())
print(sorted(dic.items(), key=lambda s: (-s[1])))
for i, v in dic.items():
if v == 1:
print(i)
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经典二叉树模版
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class TreeNode:
def __init__(self, val, left = None, right = None):
self.val = val
self.left = left
self.right = right
vals=[3,9,20,None,None,15,7]
def create_tree(vals, index=0):
if index >= len(vals) or vals[index] is None:
return None
root = TreeNode(vals[index])
root.left = create_tree(vals, 2 * index + 1)
root.right = create_tree(vals, 2 * index + 2)
return root
root = create_tree(vals)
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由labuladong算法笔记改编而来，原链接https://labuladong.online/algo/programming-language-basic/python/
