重复元素的计数是应该的两倍。

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英文:

The count of duplicate elements is double what it should be

问题

我正在处理一份旧考试题目,题目说明一个给定的数组 (int zahlen[]={1,4,5,1,5,7,9,2,3,4}) 中有相同的值。任务是将相同的值替换为 '-1'。每次替换后,要增加一个给定的变量 count 值。

我的问题是变量 count 的值是正常值的两倍(在这种情况下,只有3个相同的数字,但变量显示为6)。

该函数名为 array_unique。我将感激对我的错误进行简要解释。

这是我的代码:

#include <stdio.h>
#include <stdlib.h>

int main()
{
    system("chcp 1252");
    int zahlen[]={1,4,5,1,5,7,9,2,3,4};
    int len = sizeof(zahlen)/sizeof(int);
    int erg = array_unique(zahlen,len);
    printf("Es wurden %d doppelte Zahlen gelöscht: \n",erg);
    printf("Das Array hat nun folgende Werte: ");
    printArrayUnique(zahlen,len);
    return 0;
}

void printArrayUnique(int *array, int len){
    for(int i=0; i<len; i++){
        if(array[i]!=-1){
            printf("%d ",array[i]);

        }
    }
}

int array_unique(int *array, int len){
    int count=0;
    for(int i=0; i<len;i++){
        for(int j=i+1; j<len;j++){
            if(array[i]==array[j]){
                array[j] = -1;
                count++;
            }
        }
    }
    return count;
}

我没有找到其他解决方案来修复 count 的错误值。

英文:

I am working on an old exam and the problems states that a given array (int zahlen[]={1,4,5,1,5,7,9,2,3,4}) has values that are the same. The task is to replace the values that are the same with '-1'. After each replacement, a given variable, count, has to be increased by one.

My problem is that the variable count is two-times higher than normal (In this case there are only 3 of the same numbers and the variable shows 6.)

The function is called array_unique. I am would be grateful for a brief explanation of my mistake.

Here is my code:

#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;

int main()
{
    system(&quot;chcp 1252&quot;);
    int zahlen[]={1,4,5,1,5,7,9,2,3,4};
    int len = sizeof(zahlen)/sizeof(int);
    int erg = array_unique(zahlen,len);
    printf(&quot;Es wurden %d doppelte Zahlen gel&#246;scht: \n&quot;,erg);
    printf(&quot;Das Array hat nun folgende Werte: &quot;);
    printArrayUnique(zahlen,len);
    return 0;
}

void printArrayUnique(int *array, int len){
    for(int i=0; i&lt;len; i++){
        if(array[i]!=-1){
            printf(&quot;%d &quot;,array[i]);

        }
    }
}

int array_unique(int *array, int len){
    int count=0;
    for(int i=0; i&lt;len;i++){
        for(int j=i+1; j&lt;len;j++){
            if(array[i]==array[j]){
                array[j] = -1;
                count++;


            }
        }

    }
    return count;
}

I have not figured out any other solution to fix the faulty value of count.

答案1

得分: 1

问题是因为你多次计算了重复项;所以,当你找到重复的条目时,你会正确地将其替换为 -1,但是后来在循环中,你可能会比较两个或更多的 -1 值。

只需在递增 count 变量之前添加一个检查,检查两个值都不是 -1(以及相等测试):

int array_unique(int* array, int len)
{
    int count = 0;
    for (int i = 0; i &lt; len; i++) {
        for (int j = i + 1; j &lt; len; j++) {
            if (array[i] == array[j] &amp;&amp; array[j] != -1) {
                array[j] = -1;
                count++;
            }
        }
    }
    return count;
}

还要注意,正如评论中提到的那样,在使用函数之前,你确实需要声明它们。在 main 函数之前添加以下两行:

void printArrayUnique(int* array, int len);
int array_unique(int* array, int len);
英文:

The issue is due to the fact that your are counting duplicates more than once; so, when you have found a duplicate entry, you correctly replace that with -1 but then, later in the loops, you will be (potentially, at least) comparing two or more of those -1 values.

Just add a check that either value is not -1 (along with the test for equality) before incrementing the count variable:

int array_unique(int* array, int len)
{
    int count = 0;
    for (int i = 0; i &lt; len; i++) {
        for (int j = i + 1; j &lt; len; j++) {
            if (array[i] == array[j] &amp;&amp; array[j] != -1) {
                array[j] = -1;
                count++;
            }
        }
    }
    return count;
}

Note also that, as mentioned in the comments, you really do need declarations of your functions before you use them. Add the following two lines before the main function:

void printArrayUnique(int* array, int len);
int array_unique(int* array, int len);

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  • 本文由 发表于 2023年1月9日 18:38:11
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