Codeforces Round #286 (Div. 2) A.(回文串暴力)

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题目链接：http://codeforces.com/contest/505/problem/A

解题思路：

暴力求解，对于每一个位置，都用a到z进行插入，如果有符合条件的，直接输出。否则输出NA

完整代码：

//#include <bits/stdc++.h>#include <functional>#include <algorithm>#include <iostream>#include <fstream>#include <sstream>#include <iomanip>#include <numeric>#include <cstring>#include <climits>#include <cassert>#include <complex>#include <cstdio>#include <string>#include <vector>#include <bitset>#include <queue>#include <stack>#include <cmath>#include <ctime>#include <list>#include <set>#include <map>using namespace std;#pragma comment(linker, "/STACK:102400000,102400000")typedef long long LL;typedef double DB;typedef unsigned uint;typedef unsigned long long uLL;/*__gcd(a, b)  // My gcd__builtin_ffs(x) //My lowbit__builtin_popcount(x) //The number of 1-bits*//** Constant List .. **/ //{const int MOD = int(1e9)+7;const int INF = 0x3f3f3f3f;const LL INFF = 0x3f3f3f3f3f3f3f3fLL;const DB EPS = 1e-9;const DB OO = 1e20;const DB PI = acos(-1.0); //M_PI;string s;bool check(string t){    int len = t.length();    for(int i = 0 ,  j = len - 1 ; i < j ; i ++ , j --)    {        if(t[i] != t[j])            return false;    }    return true;}int main(){    #ifdef DoubleQ    freopen("in.txt","r",stdin);    #endif    std::ios::sync_with_stdio(false);    std::cin.tie(0);    while(cin >> s)    {        int n = s.length();        int flag = 0;        for(int i = 0 ; i <= n ; i ++)        {            for(int j = 0 ; j < 26 ; j ++)            {                string t = "";                for(int k = 0 ; k < i ; k ++)                    t += s[k];                t += (char)(j + 'a');                for(int k = i ; k < n ; k ++)                    t += s[k];                if(check(t))                {                    cout << t << endl;                    flag = 1;                    break;                }            }            if(flag)                break;        }        if(flag == 0)            cout << "NA" << endl;    }}

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