1.编写函数，对给定的整数数组a（数组长度和元素个数均为N）进行判定：是否存在某个整数a[i]（0<i<N），等于在其之前的所有整数的和

#include <stdio.h>
#include <stdbool.h>bool judge(int *a,int n) {for(int i=0; i<n; i++) {int sum=0;for(int j=0; j<i; j++)sum+=a[j];if(sum==a[i])return true;}return false;
}int main() {int a[]= {2,21,1,4,5};printf("%d",judge(a,5));
}

2.（2x+3y)^n 求第k项余数，例如（2x+3y)^3 = 8x^3 + 36x^2y + 54xy^2 + 27y^3，第二项系数为54，要求递归求第k项余数，不可使用全局遍历

#include <stdio.h>int find(int n,int k) {if(n-k==0&&k==0)return 1;if(n-k==0)return 3*find(n-1,k-1);if(k==0)return 2*find(n-1,k);return 2*find(n-1,k)+3*find(n-1,k-1);
}

3.每个教师的信息卡片包括教工号，姓名，性别，入职年份（限定为1900-2100之间的整数）四项，定义存储教师信息的单向链表的节点类型：编写函数，由当前目录下文件名为input.txt的文件依次读入n（n>=1）个教师的信息，创建一个用于管理教师信息的单向链表。

#include <stdio.h>
#include <stdlib.h>typedef struct teacher {int num;char name[20];int sex;int year;struct teacher *next;
} teacher;struct teacher *create(int n) {FILE *file;if((file=fopen("input.txt","r"))==NULL) {printf("open error");exit(0);}struct teacher *head = (struct teacher *)malloc(sizeof(struct teacher));head->next=NULL;for(int i=0; i<n; i++) {struct teacher *p = (struct teacher *)malloc(sizeof(struct teacher));fscanf(file,"%d %s %d %d",&p->num,&p->name,&p->sex,&p->year);p->next=head->next;head->next=p;}return head->next;
}struct teacher *bubble(struct teacher *head) {struct teacher *p=head,*q,*tail;int n;while(p->next!=NULL) {n++;p=p->next;}for(int i=0; i<n-1; i++) {q=head->next;p=q->next;tail=head;for(int j=0; j<n-i-1; j++) {if(q->num>p->num) {q->next=p->next;p->next=q;tail->next=p;}tail=tail->next;q=tail->next;p=q->next;}}
}struct teacher *del(struct teacher *head, int key) {struct teacher *p = head, *q;while (p != NULL) {q = p->next;if (q != NULL && q->num == key) {p->next = q->next;struct teacher *temp=q;free(temp);}p = p->next;}return head;
}struct teacher *insert(struct teacher *head) {struct teacher *p=(struct teacher *)malloc(sizeof(struct teacher));struct teacher *q=head;scanf("%d %s %d %d",&p->num,&p->name,&p->sex,&p->year);while(q->next!=NULL&&q->next->num<p->num)q=q->next;p->next=q->next;q->next=p;return head;
}

4.定义单链表（每个结点包含2个字段：整数信息，后继指针），编写函数，删除该单链表中所含整数信息等于整数x的多个重复结点。

#include <stdio.h>
#include <stdlib.h>typedef struct node{int data;struct node *next;
}node;struct node *del(struct node *head, int key) {struct node *p = head, *q;while (p != NULL) {q = p->next;if (q != NULL && q->data == key) {p->next = q->next;struct node *temp=q;free(temp);}p = p->next;}return head;
}