後序運算式
輸入 中序 輸出 後序
青年程式設計競賽 2016 2.py
python
# 題目 2：後序(Postfix)轉換問題 (10%) (中序轉後序)
st = input()
level = {'+': 1, '-': 1, '*': 2, '/': 2}
output = []
stack = []
for char in st:
if char.isalnum():
output.append(char)
elif char in '+-*/':
while (stack and (stack[-1] in '+-*/') and (level[stack[-1]] >= level[char])):
output.append(stack.pop())
stack.append(char)
elif char == '(':
stack.append(char)
elif char == ')': # 遇到括號
while stack and stack[-1] != '(':
output.append(stack.pop())
stack.pop()
print(stack,output)
while stack:
output.append(stack.pop())
print(''.join(output))輸入 後序 輸出 結果
zerojudge f698. 後序運算式
python
data = list(input().split())
stack = []
while data:
num_or_op = data.pop(0)
try: #int
eval(num_or_op)
stack.append(num_or_op)
except: #op
b = stack.pop()
a = stack.pop()
stack.append(str(eval(a+num_or_op+b)))
print(f'{float(stack[0]):.0f}')106 正試 H 後序運算式
python
for _ in range(int(input())):
line = input().split()
stack = []
for i in line:
if i.isdigit():
stack.append(i)
else:
stack.append(int(eval(f'{stack.pop()}{i}{stack.pop()}')))
print(stack[0])Contributors
lucashsu95