Problem - A - Codeforces

查有没有人说谎，有一个必错的情况：

两个人都说输了，必有人撒谎，还有就是所有人都赢了，也是撒谎

来看代码：

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

int main() 
{
	int t;
	cin >> t;
	while (t--)
	{
		int n;
		cin >> n;
		vector<int>arr(n);
		int sum = 0;
		for (int i = 0; i < n; i++)
		{
			cin >> arr[i];
			sum += arr[i];
		}
		if (sum == n)
		{
			cout << "YES" << "\n";
			continue;
		}
		int flag = 1;
		//大于3个 滑动窗口解决
		if (n > 2)
		{
			for (int i = 0; i < n - 2; i++)
			{
				int one = arr[i];
				int two = arr[i + 1];
				int thr = arr[i + 2];
				//枚举过程
				if (one == 0 && two == 0)
				{
					flag = 0;
				}
				if (two == 0 && thr == 0)
				{
					flag = 0;
				}
				
			}
		}
		else
		{
			if (arr[0] == arr[1])
			{
				flag = 0;
			}
		}
		if (flag)
		{
			cout << "NO" << "\n";
		}
		else
		{
			cout << "YES" << "\n";
		}

	}
}

Problem - B - Codeforces

如何躲得最好呢？

第一次切割：横切竖切有2种选择，我之前比较看谁切得多就切，但是会出错，所以我横竖都切一次，最后来比较

每次都躲中间，这个切就像二分，来看代码：

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

int main() 
{
	int t;
	cin >> t;
	int sum = 0;
	while (t--)
	{
		sum++;
		int a, b, c, d;
		cin >> a >> b >> c >> d;
		//第一次判断 横切还是竖切
		int height = max(a - c, c - 1);
		int broad = max(b - d, d - 1);

			int left = 0;
			int right = a - 1-height;
			int count1 = 0;
			while (left < right) {
				int mid = (left + right) >> 1;
				right = mid;
				count1++;
			}
			right = b - 1;
			while (left < right) {
				int mid = (left + right) >> 1;
				right = mid;
				count1++;
			}
			
			left = 0;
			right = a - 1;
			int count = 0;
			while (left < right) {
				int mid = (left + right) >> 1;
				right = mid;
				count++;
			}
			right = b - 1 - broad;
			while (left < right) {
				int mid = (left + right) >> 1;
				right = mid;
				count++;
			}
		

		cout << min(count1,count)+1 << "\n";
	}
}

看看错误代码：

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

int main() 
{
	int t;
	cin >> t;
	while (t--)
	{
		int a, b, c, d;
		cin >> a >> b >> c >> d;
		//第一次判断 横切还是竖切
		int height = max(a - c, c - 1);
		int broad = max(b - d, d - 1);
		//如果是横切
		if (height * b > broad * a)
		{
			a -= height;
		}
		else
		{
			b -= broad;
		}
	
		int left = 0;
		int right = a - 1;
		int count = 0;
		while (left < right) {
			int mid = (left + right) >> 1; 
			right = mid; 
			count++;
		}
		right = b - 1;
		while (left < right) {
			int mid = (left + right) >> 1;  
			right = mid;  
			count++;
		}
		cout << count+1 << "\n";
	}
}