删除数组指定的元素（难度：半颗星）

谁借莪１个温暖的怀抱￠ 2022-06-16 09:23 104阅读 0赞

给定一个数组，删除数组中指定的元素

方法1：  
把不等于要删除的数全部按照顺序从0开始排起，最后改变原数组的长度即可

参考代码：

#include<stdio.h>
    
    void DeleteElementFromArray(int *pArray, int* pnCount, int nDeleteNum)
    {
       //思路：把不等于要删除的数全部按照顺序从0开始排起，最后改变原数组的长度即可
        int i, nIndex = 0;
        for (i = 0; i < *pnCount; i++)
        {
            if (pArray[i] != nDeleteNum)
                pArray[nIndex++] = pArray[i];
        }
        *pnCount = nIndex;
    }
    
    int main()
    {
        int arr[] = { 1, 2, 1, 4, 5, 7, 8, 1 };
        int i, nCount = sizeof(arr) / sizeof(arr[0]);
        printf("删除前\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
    
        DeleteElementFromArray(arr, &nCount, 1);
    
        printf("删除后\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
        return 0;
    }

方法2：  
遇到等于要删除的数，把后面的数往前移动

参考代码：

#include<stdio.h>
    
    void DeleteElementFromArray(int *pArray, int* pnCount, int nDeleteNum)
    {
       //思路：遇到等于要删除的数，把后面的数往前移动
        int i, j;
        for (i = 0; i < *pnCount; i++)
        {
            if (pArray[i] == nDeleteNum)
            {
                for (j = i + 1; j < *pnCount; j++)
                    pArray[j - 1] = pArray[j];
                (*pnCount)--;
                i--;
            }
        }
    }
    
    int main()
    {
        int arr[] = { 1, 2, 1, 4, 5, 7, 8, 1 };
        int i, nCount = sizeof(arr) / sizeof(arr[0]);
        printf("删除前\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
    
        DeleteElementFromArray(arr, &nCount, 1);
    
        printf("删除后\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
        return 0;
    }

方法3：  
申请一个临时的数组保存一下不等于nDeleteNum，然后把它放回到原来的数组

参考代码：

#include <stdio.h>
    #include <malloc.h>
    
    void DeleteElementFromArray(int *pArray, int* pnCount, int nDeleteNum)
    {
       //思路：申请一个临时的数组保存一下不等于nDeleteNum，然后把它放回到原来的数组
        int i, nTempCount = 0;
        int *pTemp = (int*)malloc(100 * sizeof(int));
        for (i = 0; i < *pnCount; i++)
        {
            if (pArray[i] != nDeleteNum)
                pTemp[nTempCount++] = pArray[i];
        }
        for (i = 0; i < nTempCount; i++)
            pArray[i] = pTemp[i];
        *pnCount = nTempCount;
        free(pTemp);
    }
    
    int main()
    {
        int arr[] = { 1, 2, 1, 4, 5, 7, 8, 1 };
        int i, nCount = sizeof(arr) / sizeof(arr[0]);
        printf("删除前\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
    
        DeleteElementFromArray(arr, &nCount, 1);
    
        printf("删除后\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
        return 0;
    }

方法4：  
不删除只做标记，根据标记输出

参考代码：

#include <stdio.h>
    #include <malloc.h>
    #include <memory.h>
    
    int main()
    {
        int arr[] = { 1, 2, 1, 4, 5, 7, 8, 1 };
        int i, nCount = sizeof(arr) / sizeof(arr[0]);
        int *pFlag = (int*)malloc(nCount * sizeof(int));
        memset(pFlag, 0, nCount * sizeof(int));
        printf("删除前\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
    
        for (i = 0; i < nCount; i++)//不删除只做标记，根据标记输出
            if (1 == arr[i])
                pFlag[i] = 1;
    
        printf("删除后\n");
        for (i = 0; i < nCount; i++)
        {
            if (0 == pFlag[i])
                printf("%d ", arr[i]);
        }
        printf("\n");
        return 0;
    }

方法5：  
用单链表进行周转，因为单链表进行节点删除，时间复杂度为O（1）

参考代码：

#include<stdio.h>
    #include <malloc.h>
    
    typedef struct NODE
    {
        int data;
        struct NODE *pNext;
    }Node;
    
    void DeleteElementFromArray(int *pArray, int* pnCount, int nDeleteNum)
    {
       //思路：用单链表进行周转，因为单链表进行节点删除，时间复杂度为O（1）
        int i, nIndex = 0;
        Node *head, *p, *s;
        head = (Node*)malloc(sizeof(Node));
        head->data = 0;
        head->pNext = NULL;
        p = head;//先初始化一个空节点，该节点的主要目的是为了删除第一个元素
        for (i = 0; i < *pnCount; i++)
        {
            s = (Node*)malloc(sizeof(Node));
            s->data = pArray[i];
            s->pNext = NULL;
            p->pNext = s;
            p = s;
        }
        p = head;
        s = p->pNext;
        while (s)
        {
       //删除元素
            if (s->data == nDeleteNum)
            {
                p->pNext = s->pNext;
                free(s);
                s = p->pNext;
            }
            else
            {
                p = s;
                s = s->pNext;
            }
        }
        p = head->pNext;
        while (p)
        {
       //一个一个push到原来的数组中
            pArray[nIndex++] = p->data;
            p = p->pNext;
        }
        *pnCount = nIndex;//改变原来数组的长度
    }
    
    int main()
    {
        int arr[] = { 1, 2, 1, 4, 5, 7, 8, 1 };
        int i, nCount = sizeof(arr) / sizeof(arr[0]);
        printf("删除前\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
    
        DeleteElementFromArray(arr, &nCount, 1);
    
        printf("删除后\n");
        for (i = 0; i < nCount; i++)
            printf("%d ", arr[i]);
        printf("\n");
        return 0;
    }

运行结果：

![这里写图片描述][SouthEast]

[SouthEast]: /images/20220616/fa2c466da2cd42e99e30e2eda44021f1.png