Educational Codeforces Round 97 (Rated for Div. 2)

A. Marketing Scheme

#include <bits/stdc++.h>
using namespace std;
int main () {
	int t;
	cin >> t;
	while(t--) {
		int l, r;
		cin >> l >> r;
		if(r <= 2 * l - 1) {
			cout << "YES" << endl;
		}else {
			cout << "NO" << endl;
		}
	}
}

 B. Reverse Binary Strings

#include <bits/stdc++.h>
using namespace std;
int main () {
	int t;
	cin >> t;
	while(t--) {
		int n;
		cin >> n;
		string s;
		cin >> s;
		int temp1 = 0;
		int ans1 = 0;
		int temp2 = 0;
		int ans2 = 0;
		for(int i = 0; i < n; ++i) {
			if(s[i] == '1') {
				temp1++;
				ans2 += (temp2 == 0) ? 0 : temp2 - 1;
				temp2 = 0;
			} else {
				temp2++;
				ans1 += (temp1 == 0) ? 0 : temp1 - 1;
				temp1 = 0;
			}
		}
		ans1 += (temp1 == 0) ? 0 : temp1 - 1;
		ans2 += (temp2 == 0) ? 0 : temp2 - 1;
		cout << max(ans1, ans2) << endl;
	}
}

 C. Chef Monocarp

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 210;
int dp[MAXN][MAXN];
int main () {
	int T;
	cin >> T;
	while(T--) {
		int n;
		cin >> n;
		std::vector<int> v(n + 1, 1e9);
		memset(dp, 0x3f3f3f3f, sizeof dp);
		for(int i = 1; i <= n; ++i){
			cin >> v[i];
		}
		sort(v.begin() + 1, v.end());
		// dp[0][0] = 0;
		// for(int i = 1; i <= 2 * n; ++i) {
		// 	dp[i][0] = 0;
		// 	for(int j = n; j >= 1; --j) {
		// 		dp[i][j] = min(dp[i - 1][j], dp[i - 1][j - 1] + abs(v[j] - i));
		// 	}
		// }
		// cout << dp[2 * n][n] << endl;
 
		//用一个数组实现：
		int HP[MAXN];
		memset(HP, 0x3f3f3f3f, sizeof HP);
		HP[0] = 0;
		for(int i = 1; i <= 2 *n; ++i) {
			for(int j = n; j >= 1; --j) {
				HP[j] = min(HP[j], HP[j - 1] + abs(v[j] - i));
			}
		}
		cout << HP[n] << endl;
	}
}

 D. Minimal Height Tree

#include <bits/stdc++.h>
using namespace std;
int main () {
	int t;
	cin >> t;
	while(t--) {
		int n;
		cin >> n;
		std::vector<int> v(n + 1);
		std::vector<int> hp(n + 1);
		for(int i = 1; i <= n; ++i) {
			cin >> v[i];
		}
		int l = 1;
		hp[1] = 0;
		for(int i = 2; i <= n; ++i) {
			if(v[i] < v[i - 1]) {
				l++;
			}
			hp[i] = hp[l] + 1;
		}
		cout << hp[n] << endl;
	}
}