Problem: Given is a string S. Let T be the concatenation of K copies of S. We can repeatedly perform the following operation: choose a character in T and replace it with a different character. Find the minimum number of operations required to satisfy the following condition: any two adjacent characters in T are different.

Submission attempts (in order):
S = input()
K = int(input())

if(S.count(S[0]) == len(S)):
    print(len(S)*K//2)
else:
    cnt = 0
    lst = []
    tmp = S[0]
    for i in range(len(S)):
        if(tmp == S[i]):
            cnt += 1
        else:
            tmp = S[i]
            if(cnt > 1):
                lst.append(cnt)
            cnt = 1   
    if(cnt > 1):
        lst.append(cnt)
        
    ans = 0
    for i in lst:
        ans += K*(i//2)
    if(S[0] != S[-1]):
        print(ans)
    else:
        for i in range(len(S)):
            if(tmp != S[i]):
                break
            a += 1
        for i in S[::-1]:
            if(tmp != i):
                break
            b += 1
        print(ans+((a+b)//2-(a//2+b//2))*(K-1))

S = input()
K = int(input())

if(S.count(S[0]) == len(S)):
    print((len(S)*K//2)
else:
    if(S[0] != S[-1]):
        cnt = 0
        lst = []
        tmp = S[0]
        for i in range(len(S)):
            if(tmp == S[i]):
                cnt += 1
            else:
                tmp = S[i]
                if(cnt > 1):
                    lst.append(cnt)
                cnt = 1   
        if(cnt > 1):
            lst.append(cnt)
        
        ans = 0
        for i in range(len(lst)):
            ans += K*(lst[i]//2)
        print(ans)
    else:
        cnt = 0
        lst = []
        tmp = S[0]
        for i in range(len(S)):
            if(tmp == S[i]):
                cnt += 1
            else:
                tmp = S[i]
                if(cnt > 1):
                    lst.append(cnt)
                cnt = 1
        if(cnt > 1):
            lst.append(cnt)
    
        ans = 0
        for i in range(len(lst)):
            ans += K*(lst[i]//2)
        a = 0
        b = 0
        tmp = S[0]
        for i in range(len(S)):
            if(tmp != S[i]):
                break
            a += 1
        for i in S[::-1]:
            if(tmp != i):
                break
            b += 1
        print(ans+((a+b)//2-(a//2+b//2)*(K-1))

S = input()
K = int(input())

if(S.count(S[0]) == len(S)):
    print(len(S)*K//2)
else:
    if(S[0] != S[-1]):
        cnt = 0
        lst = []
        tmp = S[0]
        for i in range(len(S)):
            if(tmp == S[i]):
                cnt += 1
            else:
                tmp = S[i]
                if(cnt > 1):
                    lst.append(cnt)
                cnt = 1   
        if(cnt > 1):
            lst.append(cnt)
        
        ans = 0
        for i in range(len(lst)):
            ans += K*(lst[i]//2)
        print(ans)
    else:
        cnt = 0
        lst = []
        tmp = S[0]
        for i in range(len(S)):
            if(tmp == S[i]):
                cnt += 1
            else:
                tmp = S[i]
                if(cnt > 1):
                    lst.append(cnt)
                cnt = 1
        if(cnt > 1):
            lst.append(cnt)
    
        ans = 0
        for i in range(len(lst)):
            ans += K*(lst[i]//2)
        a = 0
        b = 0
        tmp = S[0]
        for i in range(len(S)):
            if(tmp != S[i]):
                break
            a += 1
        for i in S[::-1]:
            if(tmp != i):
                break
            b += 1
        print(ans+((a+b)//2-(a//2+b//2)*(K-1))

S = input()
K = int(input())

if(S.count(S[0]) == len(S)):
    print(len(S)*K//2)
else:
    cnt = 0
    lst = []
    tmp = S[0]
    for i in range(len(S)):
        if(tmp == S[i]):
            cnt += 1
        else:
            tmp = S[i]
            if(cnt > 1):
                lst.append(cnt)
            cnt = 1   
    if(cnt > 1):
        lst.append(cnt)
        
    ans = 0
    for i in lst:
        ans += K*(i//2)
    if(S[0] != S[-1]):
        print(ans)
    else:
        a = 0
        b = 0
        for i in range(len(S)):
            if(tmp != S[i]):
                break
            a += 1
        for i in S[::-1]:
            if(tmp != i):
                break
            b += 1
        print(ans+((a+b)//2-(a//2+b//2))*(K-1))

Verdicts: Runtime Error

Runtime Error

Runtime Error

Accepted