以下是面试要求:
String str = "1*2+3";
// 计算字符串给出的结果, 只含有加法和乘法
个人实现如下, 未作优化:
import java.util.*;
// 必须定义 `ShowMeBug` 入口类和 `public static void main(String[] args)` 入口方法
public class ShowMeBug {
public static void main(String[] args) {
//String str = "1*2+3";
// String str = "3+2+4*2";
String str = "24*5+5*2";
var result = getMathResult(str);
System.out.println(result);
}
public static String getMathResult(String str) {
Stack methodStack = new Stack();
Stack dataStack = new Stack();
var strChars = str.toCharArray();
var tmpStr = "";
for (var strChar : strChars) {
if (strChar == '*' || strChar == '+') {
methodStack.push(strChar);
dataStack.push(tmpStr);
tmpStr = "";
} else {
tmpStr += strChar;
}
}
dataStack.push(tmpStr);
var result = methCompute(dataStack, methodStack);
return String.valueOf(result);
}
private static Integer methCompute(Stack dataStack, Stack methodStack) {
var result = Integer.valueOf(dataStack.pop().toString());
var tmpMethod = methodStack.pop();
var tmpRes = Integer.valueOf(dataStack.pop().toString());
if (dataStack.size() > 0) {
while(dataStack.size() > 0) {
var tmpM = methodStack.pop();
var tmpR = Integer.valueOf(dataStack.pop().toString());
if (tmpM.equals('*')) {
tmpRes = tmpRes * tmpR;
} else {
result = tmpMethod.equals('*') ? result * tmpRes : result + tmpRes;
tmpMethod = tmpM;
tmpRes = tmpR;
}
}
}
result = tmpMethod.equals('*') ? result * tmpRes : result + tmpRes;
return result;
}
}
虽然在规定的时间没能实现, 但是还是要把他写出来保留。
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