Python | Leetcode Python题解之第306题累加数

题目:

题解:

python 复制代码
class Solution:
    def isAdditiveNumber(self, num: str) -> bool:
        n = len(num)
        for secondStart in range(1, n-1):
            if num[0] == '0' and secondStart != 1:
                break
            for secondEnd in range(secondStart, n-1):
                if num[secondStart] == '0' and secondStart != secondEnd:
                    break
                if self.valid(secondStart, secondEnd, num):
                    return True
        return False
    
    def valid(self, secondStart: int, secondEnd: int, num: str) -> bool:
        n = len(num)
        firstStart, firstEnd = 0, secondStart - 1
        while secondEnd <= n - 1:
            third = self.stringAdd(num, firstStart, firstEnd, secondStart, secondEnd)
            thirdStart = secondEnd + 1
            thirdEnd = secondEnd + len(third)
            if thirdEnd >= n or num[thirdStart:thirdEnd+1] != third:
                break
            if thirdEnd == n-1:
                return True
            firstStart, firstEnd = secondStart, secondEnd
            secondStart, secondEnd = thirdStart, thirdEnd
        return False
    
    def stringAdd(self, s: str, firstStart: int, firstEnd: int, secondStart: int, secondEnd: int) -> str:
        third = []
        carry, cur = 0, 0
        while firstEnd >= firstStart or secondEnd >= secondStart or carry != 0:
            cur = carry
            if firstEnd >= firstStart:
                cur += ord(s[firstEnd]) - ord('0')
                firstEnd -= 1
            if secondEnd >= secondStart:
                cur += ord(s[secondEnd]) - ord('0')
                secondEnd -= 1
            carry = cur // 10
            cur %= 10
            third.append(chr(cur + ord('0')))
        return ''.join(third[::-1])
相关推荐
HsuHeinrich4 分钟前
利用径向柱图探索西班牙语学习数据
python·数据可视化
独行soc12 分钟前
2025年渗透测试面试题总结-105(题目+回答)
网络·python·安全·web安全·adb·渗透测试·安全狮
史锦彪29 分钟前
用 PyTorch 实现 MNIST 手写数字识别:从入门到实践
人工智能·pytorch·python
董建光d31 分钟前
PyTorch 实现 MNIST 手写数字识别完整流程(含数据处理、模型构建与训练可视化)
人工智能·pytorch·python
小宁爱Python2 小时前
从零搭建 RAG 智能问答系统3:聊天信息持久化和登录注册
python
天才少女爱迪生3 小时前
LLVM(Low Level Virtual Machine)介绍
python·数据挖掘
碳酸的唐6 小时前
A* 工程实践全指南:从启发式设计到可视化与性能优化
python·神经网络
Swift社区8 小时前
LeetCode 394. 字符串解码(Decode String)
算法·leetcode·职场和发展
tt5555555555558 小时前
LeetCode进阶算法题解详解
算法·leetcode·职场和发展