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业务场景需要实现一个公式计算器,经过提炼成oj



题目如下:


给定一个只包括 ‘(’，’)’，’&’，’|’，‘1’，‘0’ 的字符串 s ，计算该表达式的布尔结果


注意:


其中 多重 ‘(’，’)’ 需要有计算优先级,先计算括号内部运算

‘&’ => 且

‘|’ => 或

‘1’ => true

‘0’ => false

示例 1：

输入：s = "1"
输出：true

示例 2：

输入：s = "((1&1|1&0|1)|(1&1))"
输出：true

示例 3：

输入：s = "((((1&0)|(1|0)&1)|1)|0)"
输出：true

示例 3：

输入：s = "1&1&1|1&0"
输出：false

示例 4：

输入：s = "((1&1|0|1)&(0&(0|1)))"
输出：false

解答思路:

public class MainClassC {

    @Test
    public void test(){
        System.out.println(calculate("((1&1|1&0|1)|(1&1))"));
        System.out.println(calculate("((((1&0)|(1|0)&1)|1)|0)"));
        System.out.println(calculate("1&1&1|1&0"));
        System.out.println(calculate("((1&1|0|1)&(0&(0|1)))"));
        System.out.println(calculate("1"));
    }
    public static final Character LEFT_BRACKETS = '(';
    
    public static final Character RIGHT_BRACKETS = ')';

    public boolean calculate(String targetStr){
        //逻辑表达式
        StringBuilder expression = new StringBuilder();
        //前值位逻辑
        Boolean preBol = null;
        //前值位逻辑是否存在开关
        Boolean preFlag = false;
        for (int i = 0; i < targetStr.length(); i++) {
            char temp = targetStr.charAt(i);
            //括号分割
            if (temp == LEFT_BRACKETS){
                //计算出当前左括号对应的右括号下标位置
                int j = findClosing(targetStr.substring(i));
                //递归到最小集进行计算逻辑表达式
                preBol = calculate(targetStr.substring(i+1,i+j));
                expression.append(TrueAndFalseEnum.code(preBol));
                i += j;
                preFlag = true;
            }
            //将当前数值追加至当前逻辑表达式中
            if (preBol != null && preFlag){
                preFlag = false;
                continue;
            }
            expression.append(temp);
        }
        //计算逻辑表达式结果
        return calcuteExpression(expression.toString());
    }


    /**
     * 删除所有的括号对，并返回右括号的位置
     * @param s
     * @return
     */
    private int findClosing(String s) {
        int level = 0, i = 0;
        for (i = 0; i < s.length(); i++) {
            if (s.charAt(i) == LEFT_BRACKETS) level++;
            else if (s.charAt(i) == RIGHT_BRACKETS) {
                level--;
                if (level == 0) break;
            } else continue;
        }
        return i;
    }

    /**
     * 计算逻辑表达式
     * @param expression
     * @return
     */
    public boolean calcuteExpression(String expression){
        if (expression.length() == 1){  //单个数值时
            final char c = expression.charAt(0);
            if (!SymbolConstant.symbolSet.contains(c)){
                return TrueAndFalseEnum.value(c);
            }
        }
        boolean retFlag = false;
        char left = expression.charAt(0);
        char right;
        for (int i = 0; i < expression.length(); i++) {
            final char temp = expression.charAt(i);
            if (SymbolConstant.symbolSet.contains(temp)){
                if (i+1<expression.length()){
                    //取出右值
                    right = expression.charAt(i+1);
                    //计算左右逻辑运算结果
                    //获取到计算处理类
                    final CalculateMethod calculateMethod = CalculateFactory.getCalculateMethod(temp);
                    if (calculateMethod == null){
                        System.out.println("获取对应的计算处理类未获取到,对应的符号为:"+temp);
                    }
                    //将计算结果重新赋值
                    left = TrueAndFalseEnum.code(calculateMethod.calculate(TrueAndFalseEnum.value(left), TrueAndFalseEnum.value(right)));
                    //跳一位
                    i++;
                }else{
                    System.out.println("异常 下标越界异常");
                }
            }
        }
        retFlag = TrueAndFalseEnum.value(left);
        return retFlag;
    }



}

abstract class SymbolConstant{

    public static final char AND_SYM = '&';

    public static final char OR_SYM = '|';

    public static Set<Character> symbolSet = new HashSet<>();

    static {
        symbolSet.add(AND_SYM);
        symbolSet.add(OR_SYM);
    }

}

@NoArgsConstructor
@AllArgsConstructor
@Data
class Brackets{
    Character symbol;   //括号
    Integer strIndex;   //括号在字符串中的下标位置
}

enum TrueAndFalseEnum{
    TRUE('1',true),
    FALSE('0',false);
    private char code;
    private boolean value;

    TrueAndFalseEnum(char code, boolean value) {
        this.code = code;
        this.value = value;
    }

    public static Character code(boolean value){
        for (TrueAndFalseEnum data : TrueAndFalseEnum.values()) {
            if (data.getValue() == value){
                return data.code;
            }
        }
        return null;
    }

    public static Boolean value(char code){
        for (TrueAndFalseEnum data : TrueAndFalseEnum.values()) {
            if (data.getCode() == code){
                return data.value;
            }
        }
        return null;
    }



    public char getCode() {
        return code;
    }

    public boolean getValue() {
        return value;
    }

    public void setCode(char code) {
        this.code = code;
    }

    public void setValue(boolean value) {
        this.value = value;
    }
}

class CalculateFactory{

    public static CalculateMethod getCalculateMethod(char symbol){
        switch (symbol){
            case SymbolConstant.AND_SYM:
                return new AndCalculateMethod();
            case SymbolConstant.OR_SYM:
                return new OrCalculateMethod();
        }
        return null;
    }

}

interface CalculateMethod{
    Boolean calculate(Boolean left,Boolean right);
}

class AndCalculateMethod implements CalculateMethod{

    @Override
    public Boolean calculate(Boolean left, Boolean right) {
        return left && right;
    }
}

class OrCalculateMethod implements CalculateMethod{

    @Override
    public Boolean calculate(Boolean left, Boolean right) {
        return left || right;
    }
}