Help me in solving CAESAR problem.... why it is only passing one condition

help
,
1

My issue

My code

#include <iostream>
using namespace std;

int main() {
    int q;
    cin >> q;
    while(q--)
    {
        int n;
        cin >> n;
        string S,T,U;
        cin >> S >> T >> U;
        
        int riot;
        riot = T[0]-S[0];
        
        for(int i=0;i<U.length();i++)
        {   
            if(riot>=0)
            {
            U[i] = U[i] + riot;
            if(U[i]>122) U[i] = U[i] - 26;
            }
            else
            {
                int len = U[i] - 'a';
                int diff = riot - len;
                if(riot>len)
                {
                    U[i] = 122 - diff;
                }
                else U[i] = U[i] - riot;
            }
        }
        
        cout << U << endl;
    }
	return 0;
}

Problem Link: CAESAR Problem - CodeChef

2

@dj0o7
U r getting wa because riot can also be negative according to your code so u have to take care of that too.
This in my code i have taken care all the conditions in a much simpler way hope u will get it.
include
using namespace std;

int main() {
// your code goes here
int t;
cin>>t;
while(t–)
{
int n;
cin>>n;
string s,t,u;
cin>>s>>t>>u;
int k=(t[0]-s[0]+26)%26;

    for(int i=0;i<u.size();i++)
    {
        int val=(u[i]-'a'+1+k)%26;

        if(val==0)
        val=26;
        u[i]='a'+val-1;
    }
    cout<<u<<endl;
}
return 0;

}