简单的哈希
C++ 代码
#include <iostream>
#include <cstring>
#include <algorithm>
#include <map>
using namespace std;
const int N = 200;
int a[N];
int main()
{
int n;
scanf("%d", &n);
int res = 0;
for (int i = 0; i < n; i ++ ){
int x,y;
scanf("%d%d", &x, &y);
y = y + 1;
if(a[x]!=y&&a[x]!=0){
res++;
}
a[x]=y;
}
cout << res;
return 0;
}