力扣224题、227题、772题(基本计算器)
作者:互联网
统一使用拉不拉东大佬模板
224、基本计算器I
基本思路:
括号处理使用递归
使用队列,否则会超时(不懂)
具体实现:
代码:
超时的
from collections import deque class Solution: def calculate(self, s: str) -> int: def helper(s): stack = [] sign = '+' num = 0 while len(s) > 0: c=s.pop(0) if c.isdigit(): num = 10*num + int(c) if c == '(': num = helper(s) if (not c.isdigit() and c != ' ') or len(s) == 0: if sign == '+': stack.append(num) elif sign == '-': stack.append(-num) num = 0 sign = c if c == ')': break return sum(stack) return helper(list(s))
不超时的
from collections import deque class Solution: def calculate(self, s: str) -> int: str=deque(s) def helper(s): stack = [] sign = '+' num = 0 while len(s) > 0: c=s.popleft() if c.isdigit(): num = 10*num + int(c) if c == '(': num = helper(s) if (not c.isdigit() and c != ' ') or len(s) == 0: if sign == '+': stack.append(num) elif sign == '-': stack.append(-num) num = 0 sign = c if c == ')': break return sum(stack) return helper(str)
227、基本计算器II
代码:
from collections import deque class Solution: def calculate(self, s: str) -> int: stack = [] sign = '+' num = 0 s = deque(s) while len(s) > 0: c = s.popleft() if c.isdigit(): num = 10*num + int(c) if (not c.isdigit() and c != ' ') or len(s) == 0: if sign == '+': stack.append(num) elif sign == '-': stack.append(-num) elif sign == '*': stack[-1] = stack[-1]*num elif sign == '/': stack[-1] = int(stack[-1]/float(num)) num = 0 sign = c return sum(stack)
772、基本计算器III
代码:
from collections import deque class Solution: def calculate(self,s:str)->int: str=deque(s) def helper(s:List)->int: stk=[] num=0 sign='+' while len(str)>0: c=s.popleft() if c.isdigit(): num=10*num+int(c) if c=='(': num=helper(s) if(not c.isdigit() and c!=' ') or len(s)==0: if sign=='+': stk.append(num) elif sign=='-': stk.append(-num) elif sign=='*': stk[-1]=stk[-1]*num elif sign=='/': stk[-1]=int(stk[-1]/float(num)) sign=c num=0 if c==')': break return sum(stk) return helper(str)
标签:helper,772,int,sign,力扣,num,str,227,stack 来源: https://www.cnblogs.com/zhaojiayu/p/14732034.html