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  1. #define _CRT_SECURE_NO_WARNINGS
  2. #include <bits/stdc++.h>
  3. #include <iomanip>
  4. using namespace std;
  5.  
  6. #define ll long long
  7. #define ld long double
  8. const ll MAXN = 1e6 + 5;
  9. ll spf[MAXN];
  10.  
  11. ll power(ll base, ll exp, ll mod)
  12. {
  13.     if (exp == 0)
  14.         return 1 % mod;
  15.  
  16.     ll half = power(base, exp / 2, mod);
  17.     ll ans = (half * half) % mod;
  18.  
  19.     if (exp % 2 == 1)
  20.         ans = (ans * base) % mod;
  21.  
  22.     return ans;
  23. }
  24.  
  25. ll gcd(ll a, ll b)
  26. {
  27.     if (b == 0)
  28.         return a;
  29.     return gcd(b, a % b);
  30. }
  31.  
  32. ll lcm(ll a, ll b)
  33. {
  34.     return a / gcd(a, b) * b;
  35. }
  36.  
  37. void sieve()
  38. {
  39.     for (int i = 1; i < MAXN; i++)
  40.         spf[i] = i;
  41.  
  42.     for (int p = 2; p * p < MAXN; p++)
  43.     {
  44.         if (spf[p] == p)
  45.         {
  46.             for (int i = p * p; i < MAXN; i += p)
  47.             {
  48.                 if (spf[i] == i)
  49.                     spf[i] = p;
  50.             }
  51.         }
  52.     }
  53. }
  54.  
  55. vector<pair<ll, ll>> primeFactorization(ll x)
  56. {
  57.     vector<pair<ll, ll>> factors;
  58.     while (x > 1)
  59.     {
  60.         ll prime = spf[x];
  61.         ll count = 0;
  62.  
  63.         while (x % prime == 0)
  64.         {
  65.             count++;
  66.             x /= prime;
  67.         }
  68.         factors.emplace_back(prime, count);
  69.     }
  70.     return factors;
  71. }
  72.  
  73. void generateDivisors(const vector<pair<ll, ll>> &factors, vector<ll> &divisors, ll current = 1, int index = 0)
  74. {
  75.     if (index == factors.size())
  76.     {
  77.         divisors.push_back(current);
  78.         return;
  79.     }
  80.     ll prime = factors[index].first;
  81.     ll exp = factors[index].second;
  82.  
  83.     for (int i = 0; i <= exp; i++)
  84.     {
  85.         generateDivisors(factors, divisors, current, index + 1);
  86.         current *= prime;
  87.     }
  88. }
  89.  
  90. vector<int> prefixSum(vector<int> v)
  91. {
  92.     vector<int> vc(v.size());
  93.     vc[0] = v[0];
  94.     for (int i = 1; i < v.size(); i++)
  95.     {
  96.         vc[i] = vc[i - 1] + v[i];
  97.     }
  98.  
  99.     return vc;
  100. }
  101.  
  102. ld Gamma(ld n)
  103. {
  104.     return tgammal(n);
  105. }
  106.  
  107. int main()
  108. {
  109.     ios::sync_with_stdio(false);
  110.     cin.tie(nullptr);
  111.  
  112.     string s;
  113.     cin>> s;
  114.  
  115.     bool flag=true;
  116.  
  117.     for(int i=0;i< s.length();i++)
  118.     {
  119.         if(s[i] == '?')
  120.         {
  121.             s[i]=s[s.length()-i -1]; 
  122.         }
  123.         if((s.length() % 2 != 0) && s[s.length()/2]=='?')
  124.         {
  125.             s[s.length() / 2] = 'a';
  126.         }
  127.     }
  128.  
  129.     for(int i=0;i<s.length()/2;i++)
  130.     {
  131.         if(s[i] != s[s.length()-i - 1])
  132.         {
  133.             flag=false;
  134.             break;
  135.         }
  136.     }
  137.  
  138.     if(flag)
  139.     {
  140.         cout<< s<<'\n';
  141.     }
  142.     else
  143.     {
  144.         cout<<-1<<'\n';
  145.     } 
  146.     return 0;
  147. }
Success #stdin #stdout 0.01s 5324KB
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language:

						
C++14 (clang 8.0)

					

					

						
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