Question

我是Java和编程的新手......我在实现一个游程编码程序时出现问题，其中一个字符串来自用户输入。（例如：KKKKKKKKKKKKKBCCDDDDDDDDDDDDDDDKKKKKMNUUUGGGGG)将根据他们输入的标志字符进行编码。因此，特定字符串将如下所示：$K13BCC$D15$K5MNUUU$G5

有人可以帮我找出错误吗？我一直将此作为输出：$K13BCC$D14$K4MNUUU

似乎我的程序会跳过最后一个字母，而其中一些字母却少了一个。任何帮助将不胜感激！

我为我凌乱的代码道歉。我知道它并不那么棒。试着找出这里的错误......

import java.util.Scanner;

public class RunLengthEncoding {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        System.out.print("Enter input string: ");
        String inputString = input.next();

        System.out.print("Enter flag character: ");
        String flagCharacter = input.next();

        Boolean validInput = false;

        for (int i = 0; i < inputString.length(); i++) {
            if (Character.isUpperCase(inputString.charAt(i))) {
                validInput = true;

            } else {
                System.out.print("Bad input.");
            }

        }

        char repeatedLetter = inputString.charAt(0);

        if (validInput) { // if the input is valid, continue
            int counter = 0; // set counter equal to 0
            for (int i = 0; i < inputString.length(); i++) { // iterate through the input string

                if (repeatedLetter == (inputString.charAt(i))) { // if the current letter is equal to the next
                    counter++; // increment the counter
                    repeatedLetter = inputString.charAt(i); // set the repeated letter to the next letter
                } else { // if the current letter is not equal to the next letter
                    if (counter > 3) { // and if the counter is greater than 3
                        System.out.print(flagCharacter + repeatedLetter + counter); // print the encoded string
                    } else { // if the counter is not greater than 3
                        for (int j = counter; j >= 0; j--) { // for every number in counter
                            System.out.print(repeatedLetter); // print the current repeated letter for as many times as it appears
                        }

                    }
                    repeatedLetter = inputString.charAt(i); // set the new repeated letter
                    counter = 0; // reset counter to 0

                }
            }

        }

    }

}

Answer 1

首先，您应该在外部counter块中将else变量设置为1，因为您在其前面设置了repeatedValue，并将其视为单个计数信件。您还需要考虑字符串中的最后一个字符序列，因此当您到达结尾时，您需要在循环外部使用最终if语句：

int counter = 0; // set counter equal to 0
for (int i = 0; i < inputString.length(); i++) { // iterate through the input string

    if (repeatedLetter == (inputString.charAt(i))) { // if the current letter is equal to the next
        counter++; // increment the counter
    } else { // if the current letter is not equal to the next letter
        if (counter > 3) { // and if the counter is greater than 3
            System.out.print(flagCharacter + repeatedLetter + counter); // print the encoded string
        } else { // if the counter is not greater than 3
            for (int j = counter; j > 0; j--) { // for every number in counter
                System.out.print(repeatedLetter); // print the current repeated letter for as many times as it appears
            }

        }
        repeatedLetter = inputString.charAt(i); // set the new repeated letter
        counter = 1; // reset counter to 1
    }
}

// We at the end of the string now, print everything else
if (counter > 3) { // and if the counter is greater than 3
    System.out.print(flagCharacter + repeatedLetter + counter); // print the encoded string
} else { // if the counter is not greater than 3
    for (int j = counter; j > 0; j--) { // for every number in counter
        System.out.print(repeatedLetter); // print the current repeated letter for as many times as it appears
    }

}

Answer 2

for循环状态对于初始字符计数和后续字符计数并不完全相同。

使用您的代码，我发现的最简单的修复方法是更改for循环

for (int i = 1; i < inputString.length(); i++) { // start at 1 not 0

在两种情况下都将计数器初始化更改为1而不是0。

int counter = 1; // set counter equal to 1

并且必须更改单个字符输出

for (int j = counter; j > 0; j--) { // for every number in counter

也没有输出最后一个字符。

给

private static void process(String inputString, String flagCharacter) {

    // init counter state
    char repeatedLetter = inputString.charAt(0);
    int counter = 1;

    for (int i = 1; i < inputString.length(); i++) {

        if (repeatedLetter == (inputString.charAt(i))) {
            // match so update counter
            counter++;
        } else {
            if (counter > 3) {
                // counter needs to be above 3 to make worthwhile
                System.out.print(flagCharacter + repeatedLetter + counter);
            } else {
                // otherwise we will just output raw 
                for (int j = counter; j > 0; j--) {
                    System.out.print(repeatedLetter);
                }

            }
            // and re init our counter
            repeatedLetter = inputString.charAt(i);
            counter = 1;
        }

    }

    // output last character run
    if (counter > 3) {
        System.out.print(flagCharacter + repeatedLetter + counter);
    } else {
        for (int j = counter; j > 0; j--) {
            System.out.print(repeatedLetter);
        }
    }

}

运行长度编码程序问题

2 个答案: