《考研机试》（三）机试题精讲

1.题（一）

代码：

#include <iostream>
#include <iomanip> 
#include <math.h>
#include <string.h>
using namespace std;

int main(){
	int w[17] = { 7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2 };
	char check[] = { '1','0','x','9','8','7','6','5','4','3','2' };
	char s[18] = {'0'};
	cout << "输入身份证号:" << endl;
	cin >> s;
	if( strlen(s)!=18 ){
		cout << "身份证号输入错误" << endl; 
	}
	
	int b[18] = {0};//将输入的身份证号都转化为int型 
	for(int i=0; i<18; i++){
		b[i] = s[i] - '0';//字符转为int型 
	}
	
	int sum = 0;//前17位求和 
	for(int i=0; i<17; i++){
		sum += b[i]*w[i]; 
	}  
	//求出x，y 
	int x = sum%11;
	int y = check[x] - '0';
	
	if( y==b[17] ){
		cout << s << ":正确" << endl; 
	}else{
		for(int i=0; i<17; i++){
			cout << s[i] <<"";
		}
		if(check[x]=='x')
	 	    cout << 'x' << ":错误" << endl; 
		else
			cout << y << ":错误" << endl;
	}
	
	return 0;
} 

2.题（二）

 代码：

#include <iostream>
#include <iomanip> 
#include <math.h>
#include <string.h>
using namespace std;

int count = 0; 

int half_find(int a[], int l, int r, int find){
	/*
	int mid = l + (r-l)/2;
	if( l==r ) return -1;//没有找到
	if( find==a[mid] ) return mid;//恰好是中点
	if( find>a[mid] ) return half_find(a, mid+1, r, find);
	if( find<a[mid] ) return half_find(a, 0, mid, find); 
	*/
	//非递归
	int left = l;
	int right = r;
	int mid;
	
	while( left<=right ){
		count++; 
		mid = left + (right-left)/2;
		if( find==a[mid] ){
			return mid;
		}else if( find>a[mid] ){
			left = mid + 1;
		}else{
			right = mid - 1;
		}
	}
	/*
	while( left<right ){
		count++; 
		mid = left + (right-left)/2;
		if( find==a[mid] ){
			return mid;
		}else if( find>a[mid] ){
			left = mid + 1;
		}else{
			right = mid;
		}
	}
	*/
	return -1;//没找到 
}

int halffind(int a[], int len, int find){
	return half_find(a, 0, len-1, find);
}

int main(){
	int a[10] = {-36, -25, 0, 12, 14, 29, 35, 47, 76, 100};
	int find;
	cout << "查找数字：" << endl;
	cin >> find; 
	int index = halffind(a, 10, find);
	
	if( -1==index )
		cout << "没有找到" << endl;
	else 
        cout << find << "是第" << index+1 << "个数，查找次数为" << count << endl; 
	
	return 0;
} 

3.题（三）

代码：

#include<iostream>
using namespace  std ;

//定义结构体 
typedef struct {
	char name[20];
	float score1;
	float score2;
	float score3;
	int total;
}Student;

//交换 
void swap1(Student s[], int i, int j){
	Student temp = s[i];
	s[i] = s[j];
	s[j] = temp;
}

void find_fail(Student s[],int n) {
	//输出不及格的人数
	for (int i = 0; i < n; i++) {
		if (s[i].score1 < 60 || s[i].score2 < 60 || s[i].score3 < 60)
		   cout << "*[" << s[i].name << "] " << s[i].score1 << " " << s[i].score2
		   		<< " " << s[i].score3 <<  endl ;
	}
 	cout <<  endl ;
}

//按照平均成绩的高低输出
void printByAverage(Student s[],int n) {
	//按照基本的冒泡排序法按照成绩排序
	for (int i = 0; i < n - 1; i++){
		for (int j = 0; j < n-1-i; j++){
			if(s[j].total>s[j+1].total)//逆序
	   		    swap1(s,j,j+1);
		}		
	}   
	//输出 
	for(int k = n-1; k >=0; k--) {
		cout << s[k].name << " ";
		cout << s[k].score1 << " ";
		cout << s[k].score2 << " ";
		cout << s[k].score3 << endl;
	}
}

int main() {
	cout << "输入学生的人数：";
	int n = 0;
	cin >> n;
	Student s[100];//假定最多输入 100 个学生的成绩
	cout << "请依次输入学生的姓名，第一门课的成绩，第二门课的成绩，第三门课的成绩以及总分：" <<  endl ;
	for (int i = 0; i < n; i++) {
		cin >> s[i].name;
		cin >> s[i].score1;
		cin >> s[i].score2;
		cin >> s[i].score3;
		cin >> s[i].total;
	}
	find_fail(s, n);
	printByAverage(s, n);
	return 0;
}