(Niuke) BFS

Initial error code ：（ The compiler submitted said it was a segment error , We don't understand , Woo woo ）

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<iostream>
#include<queue>
#include<map>
#include<vector>
using namespace std;
//typedef long long ll;
const int N=5;
int main()
{
    
  string s;
  cin>>s;
  int flag=0;
  int mark;
  for(int i=0;i<s.size()-2;i++)
  {
    
  	if(s[i]=='B'||s[i]=='b')
  	{
    
  		if(s[i+1]=='o'||s[i+1]=='O')
  		{
    
  			if(s[i+2]=='B'||s[i+2]=='b')
  			{
    
  				flag=1;
  		cout<<i<<endl;
  		break;
			  }
		  }
  		
	  }
  }
  if(flag==0)
   cout<<"-1"<<endl; 
	return 0;
}

Correct code 1：

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<iostream>
#include<queue>
#include<map>
#include<vector>
using namespace std;
//typedef long long ll;
const int N=5;
int main()
{
    
  string s;
  cin>>s;
  for(int i=0;i<s.size();i++)
  {
    
  	s[i]=toupper(s[i]);// Capitalize all characters ,tolower Is to make all characters lowercase 
  }
  int mark;
 if((mark=s.find("BOB"))!=string::npos)// Look for the first appearance BOB when , first B The subscript 
 cout<<mark<<endl;
 else
 cout<<"-1"<<endl;
	return 0;
}

Correct code 2：

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<iostream>
#include<queue>
#include<map>
#include<vector>
using namespace std;
//typedef long long ll;
const int N=5;
int main()
{
    
  string s;
  cin>>s;
  for(int i=0;i<s.size();i++)
  {
    
  	s[i]=toupper(s[i]);
  }
  int flag=0;
  for(int i=0;i<s.size();i++)
  {
    
  	if(s[i]=='B'&&s[i+1]=='O'&&s[i+2]=='B')
  	{
    
  		cout<<i<<endl;
  		flag=1;
  		break;
	  }
  }
  if(flag==0)
  cout<<"-1"<<endl;
	return 0;
}

// The feeling is that it is wrong that the characters are not unified into positive and negative case