个人技术流程（四则运算）--王潮玉

一，分析需求

使用Java编程语言，完成一个随机生成四则运算练习的程序，可生成答案

二、设计实现

建一个Main类，写实现功能的代码

三、代码部分

package org;

import java.util.Stack;

public class Main {

    private static String[] op = { "+", "-", "*", "/" };// Operation set
    public static void main(String[] args) {
        String question = MakeFormula();
        System.out.println(question);
        String ret = Solve(question);
        System.out.println(ret);
    }

    public static String MakeFormula(){
        StringBuilder build = new StringBuilder();
        int count = (int) (Math.random() * 2) + 1; 

// generate random count
        int start = 0;
        int number1 = (int) (Math.random() * 99) + 1;
        build.append(number1);
        while (start <= count){
            int operation = (int) (Math.random() * 3); 

// generate operator
            int number2 = (int) (Math.random() * 99) + 1;
            build.append(op[operation]).append(number2);
            start ++;
        }
        return build.toString();
    }

    public static String Solve(String formula){
        Stack<String> tempStack = new Stack<>();//Store number or operator
        Stack<Character> operatorStack = new Stack<>();//Store operator
        int len = formula.length();
        int k = 0;
        for(int j = -1; j < len - 1; j++){
            char formulaChar = formula.charAt(j + 1);
            if(j == len - 2 || formulaChar == '+' || formulaChar == '-' || formulaChar == '/' || formulaChar == '*') {
                if (j == len - 2) {
                    tempStack.push(formula.substring(k));
                }
                else {
                    if(k < j){
                        tempStack.push(formula.substring(k, j + 1));
                    }
                    if(operatorStack.empty()){
                        operatorStack.push(formulaChar); //if operatorStack is empty, store it
                    }else{
                        char stackChar = operatorStack.peek();
                        if ((stackChar == '+' || stackChar == '-')
                                && (formulaChar == '*' || formulaChar == '/')){
                            operatorStack.push(formulaChar);
                        }else {
                            tempStack.push(operatorStack.pop().toString());
                            operatorStack.push(formulaChar);
                        }
                    }
                }
                k = j + 2;
            }
        }
        while (!operatorStack.empty()){ // Append remaining operators
            tempStack.push(operatorStack.pop().toString());
        }
        Stack<String> calcStack = new Stack<>();
        for(String peekChar : tempStack){ // Reverse traversing of stack
            if(!peekChar.equals("+") && !peekChar.equals("-") && !peekChar.equals("/") && !peekChar.equals("*")) {
                calcStack.push(peekChar); // Push number to stack
            }else{
                int a1 = 0;
                int b1 = 0;
                if(!calcStack.empty()){
                    b1 = Integer.parseInt(calcStack.pop());
                }
                if(!calcStack.empty()){
                    a1 = Integer.parseInt(calcStack.pop());
                }
                switch (peekChar) {
                    case "+":
                        calcStack.push(String.valueOf(a1 + b1));
                        break;
                    case "-":
                        calcStack.push(String.valueOf(a1 - b1));
                        break;
                    case "*":
                        calcStack.push(String.valueOf(a1 * b1));
                        break;
                    default:
                        calcStack.push(String.valueOf(a1 / b1));
                        break;
                }
            }
        }
        return formula + "=" + calcStack.pop();
    }
}

运行结果：

四、psp时间表

PSP阶段	计划完成时间	实际完成时间
计划	8	15
·明确需求和其他相关元素，估计每个阶段的时间成本	8	15
开发	88	85
·需求分析	10	10
·生成设计文档	6	8
·设计复审	6	8
·代码规范	5	10
·具体设计	15	30
·具体编码	60	80
·代码复审	10	3
·测试	5	3
报告	10	8
·测试报告	3	2
·设计工作量	2	2
·事后总结，并提出过程改进计划	3	2

五、总结

一开始拿到这个题目觉得不是特别难，但是上手的时候发现于想象中的不同，完全按照流程开发比较有逻辑，按部就班，显得不会那么乱，思路清晰。