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