From 3fb923694db6cdd6a1b38f16cfcc294bfa415876 Mon Sep 17 00:00:00 2001 From: Steve2020 <841532108@qq.com> Date: Sat, 22 Jan 2022 22:20:24 +0800 Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=EF=BC=880150.=E9=80=86?= =?UTF-8?q?=E6=B3=A2=E5=85=B0=E8=A1=A8=E8=BE=BE=E5=BC=8F=E6=B1=82=E5=80=BC?= =?UTF-8?q?.md=EF=BC=89=EF=BC=9A=E5=A2=9E=E5=8A=A0typescript=E7=89=88?= =?UTF-8?q?=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- problems/0150.逆波兰表达式求值.md | 65 +++++++++++++++++++++++ 1 file changed, 65 insertions(+) diff --git a/problems/0150.逆波兰表达式求值.md b/problems/0150.逆波兰表达式求值.md index f44703f1..f4dad823 100644 --- a/problems/0150.逆波兰表达式求值.md +++ b/problems/0150.逆波兰表达式求值.md @@ -210,6 +210,71 @@ var evalRPN = function(tokens) { }; ``` +TypeScript: + +普通版: + +```typescript +function evalRPN(tokens: string[]): number { + let helperStack: number[] = []; + let temp: number; + let i: number = 0; + while (i < tokens.length) { + let t: string = tokens[i]; + switch (t) { + case '+': + temp = helperStack.pop()! + helperStack.pop()!; + helperStack.push(temp); + break; + case '-': + temp = helperStack.pop()!; + temp = helperStack.pop()! - temp; + helperStack.push(temp); + break; + case '*': + temp = helperStack.pop()! * helperStack.pop()!; + helperStack.push(temp); + break; + case '/': + temp = helperStack.pop()!; + temp = Math.trunc(helperStack.pop()! / temp); + helperStack.push(temp); + break; + default: + helperStack.push(Number(t)); + break; + } + i++; + } + return helperStack.pop()!; +}; +``` + +优化版: + +```typescript +function evalRPN(tokens: string[]): number { + const helperStack: number[] = []; + const operatorMap: Map number> = new Map([ + ['+', (a, b) => a + b], + ['-', (a, b) => a - b], + ['/', (a, b) => Math.trunc(a / b)], + ['*', (a, b) => a * b], + ]); + let a: number, b: number; + for (let t of tokens) { + if (operatorMap.has(t)) { + b = helperStack.pop()!; + a = helperStack.pop()!; + helperStack.push(operatorMap.get(t)!(a, b)); + } else { + helperStack.push(Number(t)); + } + } + return helperStack.pop()!; +}; +``` + python3 ```python