USACO Monthly Tournament January 2021 Bronze Division

first question

#include <iostream>
#include <cstdio>
#include <map>
using namespace std;

map<char, int> m;

int main() {
    
    
	char ch;
	for (int i = 1; i <= 26; i ++) {
    
    
		cin >> ch;
		m[ch] = i;
	}

	int pos = 27, cnt = 0;
	while (cin >> ch) {
    
    
		if (m[ch] <= pos) {
    
    
			cnt ++;
		}
		pos = m[ch];
	}
	
	cout << cnt;

	return 0;
}

Second question

#include <iostream>
#include <cstdio>
using namespace std;

int n, x, c0, c1;

int main() {
    
    
	cin >> n;
	for (int i = 1; i <= n; i ++) {
    
    
		cin >> x;
		
		if (x%2 == 0) c0 ++;
		else c1 ++;
	}

	while (c0 < c1) {
    
    
		c1 -= 2;
		c0 += 1;
	}

	if (c0 > c1) {
    
    
		cout << c1 * 2 + 1;
	}	
	else if (c0 == c1) {
    
    
		cout << c1 * 2;
	}

	return 0;
}

Third question

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;

const int N = 30;
int n, a[N], b[N], c[N];
long long ans = 1;

int main() {
    
    
	cin >> n;
	for (int i = 1; i <= n; i ++) cin >> a[i];
	for (int i = 1; i <= n; i ++) cin >> b[i];
	
	sort(a+1, a+1+n);
	sort(b+1, b+1+n);
	
	for (int i = 1; i <= n; i ++) {
    
    	
		for (int j = 1; j <= n; j ++) {
    
    
			if (b[j] >= a[i]) c[i] ++;
		}
	}

	int t = 0;
	for (int i = n; i >= 1; i --) {
    
    
		ans *= (c[i]-t);
		t ++;
	}

	cout << ans;
	
	return 0;
}