URAL 2037 Richness of binary words （回文子串，找规律）

Richness of binary words

题目链接：

http://acm.hust.edu.cn/vjudge/contest/126823#problem/B

Description

For each integer i from 1 to n, you must print a string s i of length n consisting of letters ‘a’ and ‘b’ only. The string s i must contain exactly i distinct palindrome substrings. Two substrings are considered distinct if they are different as strings.

Input

The input contains one integer n (1 ≤ n ≤ 2000).

Output

You must print n lines. If for some i, the answer exists, print it in the form “ i : s i” where s i is one of possible strings. Otherwise, print “ i : NO”.

Sample Input

input output
4
1 : NO
2 : NO
3 : NO
4 : aaaa

题意：

要求输出n个长度为n的字符串(只能放a或b)：
要求Si中不同回文子串的个数恰为i.

题解：

本质就是找出一种构造方式使得回文子串个数不会再增加.
参考2015-ICPC合肥现场赛H题：
http://blog.csdn.net/snowy_smile/article/details/49870109
http://blog.csdn.net/keshuai19940722/article/details/49839359

代码：

#include 
#include 
#include 
#include 
#include 
#include 
#include 

转载于:https://www.cnblogs.com/Sunshine-tcf/p/5746764.html