Question

来自用户的String输入。这是一个多项式。如何在不使用数组的情况下派生此polinom ？

ınput= 3x^4+5x^45-2+77x^100

输出必须为12x^3 + 225x^44 + 7700x^99

我怎么知道多项式中有多少个x语句？

我的代码是：

String katsayi = polinom.substring(0, polinom.indexOf("x")); String us = polinom.substring(a + 1); int katSayi = Integer.parseInt(katsayi); int uS = Integer.parseInt(us); katSayi = katSayi * uS; uS = uS - 1; katsayi = Integer.toString(katSayi); us = Integer.toString(uS); yeniPolinom = katsayi + "x^" + us; System.out.println(yeniPolinom);

Answer 1

解析看起来像多项式的字符串可能非常繁琐，因为有数百种写下相同多项式的方法。但是，如果我们坚持格式ax^n，您可以查看此答案以提取多项式的系数：https://stackoverflow.com/a/13415745/1743880。

考虑使用Polynom方法制作derivative课程。

Answer 2

如何使用regex查找格式为[number1]x^[number2]的部分，然后用[num1]*[num2]x^[num2 - 1]替换此部分？以下是根据找到的值动态创建替换零件的示例。

String input = "3x^4+5x^45-2+77x^100";

Pattern p = Pattern.compile("(\\d+)x\\^(\\d+)");
//                            ^^^^      ^^^^
//                           group1    group2
Matcher m = p.matcher(input);
StringBuffer sb = new StringBuffer();
while (m.find()) {
    int a = Integer.parseInt(m.group(1));
    int n = Integer.parseInt(m.group(2));
    if (n != 0)
        m.appendReplacement(sb, (a * n) + "x^" + (n - 1));
    else
        m.appendReplacement(sb, "0");
}
m.appendTail(sb);
String output = sb.toString();
System.out.println(output);

输出：12x^3+225x^44-2+7700x^99

请注意，此解决方案非常有限。它假设所有部分都将以ax^n形式编写，因此对于x^2而不是1x^2或-1而不是{{1}这样的数据无效}。我还假设-1x^0不是负数。

Answer 3

 public static void main(String[] args) throws IOException {
        String polynomial = "3x^4+5x^45-2+77x^100";
        int lastNumber = 0;
        int temp = 0;
        String output = "";
        for(int i = 0; i < polynomial.length() - 1; i++)
        {
            if(polynomial.charAt(i) == 'x')
            {
                int counter = i + 1;
                int a = 0;
                int b = 0;
                String tempString1 = "";
                String tempString2 = "";
                String number = "";
                while((polynomial.charAt(counter) != '0') && (polynomial.charAt(counter) != '1') && (polynomial.charAt(counter) != '2') && (polynomial.charAt(counter) != '3') && (polynomial.charAt(counter) != '4') && (polynomial.charAt(counter) != '5') && (polynomial.charAt(counter) != '6') && (polynomial.charAt(counter) != '7') && (polynomial.charAt(counter) != '8') && (polynomial.charAt(counter) != '9'))
                {
                    tempString1 += polynomial.charAt(counter);
                    counter++;
                }
                while((counter < polynomial.length()) && ((polynomial.charAt(counter) == '0') || (polynomial.charAt(counter) == '1') || (polynomial.charAt(counter) == '2') || (polynomial.charAt(counter) == '3') || (polynomial.charAt(counter) == '4') || (polynomial.charAt(counter) == '5') || (polynomial.charAt(counter) == '6') || (polynomial.charAt(counter) == '7') || (polynomial.charAt(counter) == '8') || (polynomial.charAt(counter) == '9')))
                {
                    number += polynomial.charAt(counter);
                    counter++;
                }
                a = Integer.parseInt(number);
                temp = counter - 1;
                counter = i - 1;
                number = "";
                while((polynomial.charAt(counter) != '0') && (polynomial.charAt(counter) != '1') && (polynomial.charAt(counter) != '2') && (polynomial.charAt(counter) != '3') && (polynomial.charAt(counter) != '4') && (polynomial.charAt(counter) != '5') && (polynomial.charAt(counter) != '6') && (polynomial.charAt(counter) != '7') && (polynomial.charAt(counter) != '8') && (polynomial.charAt(counter) != '9'))
                {
                    tempString2 = polynomial.charAt(counter) + tempString2;
                    counter--;
                }
                while((counter >= 0) && ((polynomial.charAt(counter) == '0') || (polynomial.charAt(counter) == '1') || (polynomial.charAt(counter) == '2') || (polynomial.charAt(counter) == '3') || (polynomial.charAt(counter) == '4') || (polynomial.charAt(counter) == '5') || (polynomial.charAt(counter) == '6') || (polynomial.charAt(counter) == '7') || (polynomial.charAt(counter) == '8') || (polynomial.charAt(counter) == '9')))
                {
                    number = polynomial.charAt(counter) + number;
                    counter--;
                }
                b = Integer.parseInt(number);
                for(int j = lastNumber; j <= counter; j++)
                {
                    output += polynomial.charAt(j);
                }
                output += "" + (a * b) + "x^" + (a - 1);
                lastNumber = temp + 1;
                i = temp;
            }
        }
        System.out.println(output);
    }

输出：

12x^3+225x^44-2+7700x^99

派生多项式使用String方法

3 个答案: