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Search I

You are given a sequence of n integers S and a sequence of different q integers T. Write a program which outputs C, the number of integers in T which are also in the set S.

Input

In the first line n is given. In the second line, n integers are given. In the third line q is given. Then, in the fourth line, q integers are given.

Output

Print C in a line.

Constraints

• n ≤ 10000
• q ≤ 500
• 0 ≤ an element in S ≤ 109
• 0 ≤ an element in T ≤ 109

Sample Input 1

5
1 2 3 4 5
3
3 4 1

Sample Output 1

3

Sample Input 2

3
3 1 2
1
5

Sample Output 2

0

Sample Input 3

5
1 1 2 2 3
2
1 2

Sample Output 3

2

向线性搜索中引入"标记"可以将算法效率提高常数倍, 所谓标记, 就是我们在数组等数据结构中设置一个拥有特殊值地元素, 从而达到简化循环控制等诸多目的.
在线性搜索中, 我们可以把含有目标关键字的数据放在数组末尾, 用作标记

#include <iostream>
using namespace std;
int a[10005], b[505];
int n, q;

int search(int *a, int c)
{
	int idx = 0;
	a[n] = c;
	while(a[idx] != a[n])	idx ++;
	
	return idx != n;
}

int main()
{
	int sum = 0;
	cin >> n;
	for(int i = 0; i < n; ++ i)
		cin >> a[i];
	
	cin >> q;
	for(int i = 0; i < q; ++ i)
	{
		cin >> b[i];
		if(search(a, b[i]))	sum ++;
	}
	
	cout << sum << endl;
	
	return 0;
}

Linear Search

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原文地址：https://www.cnblogs.com/mjn1/p/10744231.html