Codeforces Round #604 (Div. 2) A. Beautiful String

链接：

https://codeforces.com/contest/1265/problem/A

题意：

A string is called beautiful if no two consecutive characters are equal. For example, "ababcb", "a" and "abab" are beautiful strings, while "aaaaaa", "abaa" and "bb" are not.

Ahcl wants to construct a beautiful string. He has a string s, consisting of only characters 'a', 'b', 'c' and '?'. Ahcl needs to replace each character '?' with one of the three characters 'a', 'b' or 'c', such that the resulting string is beautiful. Please help him!

More formally, after replacing all characters '?', the condition si≠si+1 should be satisfied for all 1≤i≤|s|−1, where |s| is the length of the string s.

思路：

直接暴力枚举，判断一遍

代码：

#include<bits/stdc++.h>
using namespace std;

string s;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int t;
    cin >> t;
    while(t--)
    {
        cin >> s;
        bool flag = true;
        for (int i = 0;i < s.length();i++)
        {
            if (s[i] == '?')
            {
                int t = -1;
                for (int j = 0;j < 3;j++)
                {
                    if ((i-1 < 0 || s[i-1] != (char)('a'+j)) && (i+1 >= s.length() || s[i+1] != (char)('a'+j)))
                    {
                        t = j;
                        break;
                    }
                }
                s[i] = (char)('a'+t);
            }
        }
        for (int i = 1;i < s.length();i++)
        {
            if (s[i] == s[i-1])
                flag = false;
        }
        cout << (flag ? s : "-1") << endl;
    }

    return 0;
}