7.29周赛

• codeforces401C

给出0和1的个数，求出数列，1不能有三个连续，0不能有两个连续

#include<cstdio>
#include<string>
#include<iostream>
#include<algorithm>
#include<map>
using namespace std;
const int maxn=200000+5;
int main()
{
	int n,m,t;
	scanf("%d%d",&n,&m);
	if(m%2==0) t=m/2-1;
	else t=m/2;
	if(n>=t&&n<=m+1)
	{
		while(n>0||m>0)
		{
		if(n==m+1)
		{
			printf("0");
			n--;
		}
		else if(n>0&&m>n&&m<=2*n+2)
		{
			printf("110");
			m-=2;
			n--;
		}
		else
		{
			printf("1");
			m--;
		}
	    }
	    printf("\n");
	}
	else
	{
		printf("-1\n");
	}
	return 0;
 } 

• codeforces999B

For example, the above algorithm applied to the string ss ="codeforces" leads to the following changes: "codeforces" →→ "secrofedoc" →→ "orcesfedoc" →→ "rocesfedoc" →→ "rocesfedoc" (obviously, the last reverse operation doesn't change the string because d=1).

每次除以二，除以二，即取字符串长度的因子，用reverse（s.begin(),s.end()），开始和结束的位置。

#include<cstdio>
#include<string>
#include<iostream>
#include<algorithm>
#include<map>
using namespace std;
const int maxn=200000+5;
int main()
{
	string s;
	int n;
	scanf("%d",&n);
	cin>>s;
	int j=1;
	while(j<=n)
	{
		if(n%j==0)
		{
			reverse(s.begin(),s.begin()+j);
		}
		j++; 
	}
	cout<<s<<endl;
	return 0;
 }