Codeforces Round #265 (Div. 2) C. No to Palindromes! 构造不含回文子串的串_html/css_WEB-ITnose

#include <cstdio>#include <cstdlib>#include <cmath>#include <cstring>#include <string>#include <queue>#include <vector>#include<set>#include <iostream>#include <algorithm>using namespace std;#define RD(x) scanf("%d",&x)#define RD2(x,y) scanf("%d%d",&x,&y)#define clr0(x) memset(x,0,sizeof(x))typedef long long LL;int p,n;char ch[1005],ans[1005];//int fun(int low, int high, char *str, int length)//{//    if (length == 0 || length == 1)//        return    1;//    if (str[low] != str[high])//        return    0;//    return fun(low+1, high-1, str, length-2);//}int fun(int low, int high, char *str, int length){    if (length == 0 || length == 1)        return  false;    if(str[low] == str[low+1])        return  true;    for(int i = low + 2;i <= high;++i){        if(str[i] == str[i-1] || str[i] == str[i-2])            return true;    }    return false;}bool find(int x,bool big){    if(x == n){        if(strcmp(ch,ans) == 0)            return false;        return true;    }    for(char i = big?'a':ch[x];i < p+'a';++i){        ans[x] = i;        int j;        if(fun(0,x,ans,x+1))    continue;//        for(j = 0;j < x;++j)//            if(fun(j,x,ans,x-j+1))//                break;//        if(j != x)  continue;        if(find(x+1,big|ans[x] > ch[x]))            return true;    }    return false;}int main() {    RD2(n,p);    scanf("%s",ch);    ans[n] = '\0';    if(find(0,0))        puts(ans);    else        puts("NO");    return 0;}