ANTS

Code

#include        <bits/stdc++.h>
#define pb      push_back
#define fi      first
#define se      second
#define int     long long 
#define pii     pair<long long, long long>
#define endl    "\n"
#define TIME    (1.0 * clock() / CLOCKS_PER_SEC)
#define FILE(A) freopen(A".INP", "r", stdin); freopen(A".OUT", "w", stdout)

using namespace std;

const int N    = 2e5+5;
const int oo   = 1e16 ;
const int MOD  = 1e9+7;
const int BASE = 31   ;

int n,a[N], b[N];
bool mark[N];

void sub1() {
	memset(mark, false, sizeof mark);
    int ans = 0;
    for (int i=1;i <= n;i++) {
    	int num = b[i], Top;
    	for (int j=1;j <= n;j++) {
    		if (mark[a[j]]) continue;
    		Top = a[j];
    		break;
    	}
    	if (num != Top) 
    		ans++;
    	mark[num] = true;
    }
    cout << ans;
}

void sub2() {
	memset(mark, false, sizeof mark);
    int ans = 0;
    int j=1;
    for (int i=1;i <= n;i++) {
    	int num = b[i];
    	while(mark[a[j]]) {
    		j++;
    	}
    	if (num != a[j]) 
    		ans++;
    	mark[num] = true;
    }
    cout << ans;
}

signed main(){
    ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	FILE("ANTS");
	cin >> n;
	for (int i=1;i <= n;i++) 
		cin >> a[i];
	for (int i=1;i <= n;i++)
		cin >> b[i];
    // sub1();
	sub2();
    
    cerr << "Time elapsed: " << TIME << "s.\n";
    return 0;
}

// Nguyen Minh Hieu - 2008 - Gia Lai.
// https://hieuhfgr.pythonanywhere.com/