Linear Search
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; }