D - Menagerie

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Time limit : 2sec / Memory limit : 256MB

Score : 500 points

Problem Statement

Snuke, who loves animals, built a zoo.

There are N animals in this zoo. They are conveniently numbered 1 through N, and arranged in a circle. The animal numbered i(2≤i≤N−1) is adjacent to the animals numbered i−1 and i+1. Also, the animal numbered 1 is adjacent to the animals numbered 2 and N, and the animal numbered N is adjacent to the animals numbered N−1 and 1.

There are two kinds of animals in this zoo: honest sheep that only speak the truth, and lying wolves that only tell lies.

Snuke cannot tell the difference between these two species, and asked each animal the following question: "Are your neighbors of the same species?" The animal numbered i answered s_i. Here, if s_i is o, the animal said that the two neighboring animals are of the same species, and if s_i is x, the animal said that the two neighboring animals are of different species.

More formally, a sheep answered o if the two neighboring animals are both sheep or both wolves, and answered x otherwise. Similarly, a wolf answered x if the two neighboring animals are both sheep or both wolves, and answered o otherwise.

Snuke is wondering whether there is a valid assignment of species to the animals that is consistent with these responses. If there is such an assignment, show one such assignment. Otherwise, print -1.

Constraints

• 3≤N≤10⁵
• s is a string of length N consisting of o and x.

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Input

The input is given from Standard Input in the following format:

Ns

Output

If there does not exist an valid assignment that is consistent with s, print -1. Otherwise, print an string t in the following format. The output is considered correct if the assignment described by t is consistent with s.

• t is a string of length N consisting of S and W.
• If t_i is S, it indicates that the animal numbered i is a sheep. If t_i is W, it indicates that the animal numbered i is a wolf.

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Sample Input 1

6ooxoox

Sample Output 1

SSSWWS

For example, if the animals numbered 1, 2, 3, 4, 5 and 6 are respectively a sheep, sheep, sheep, wolf, wolf, and sheep, it is consistent with their responses. Besides, there is another valid assignment of species: a wolf, sheep, wolf, sheep, wolf and wolf.

Let us remind you: if the neiboring animals are of the same species, a sheep answers o and a wolf answers x. If the neiboring animals are of different species, a sheep answers x and a wolf answers o.

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Sample Input 2

3oox

Sample Output 2

-1

Print -1 if there is no valid assignment of species.

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Sample Input 3

10oxooxoxoox

Sample Output 3

SSWWSSSWWS

题目链接：

题意：n只动物从1到n围成一个圈，每只动物要么是羊要么是狼。每只动物会说出一个字母，说'o'表示它两边动物种类相同，说'x'表示不同。但羊是说真话，狼是说反话。求出这n只动物的种类。

分析：模拟一下就可以了，不过这个模拟比较大！

下面给出AC代码：

1 #include 
       
          2 using namespace std;  3 const int N=123456;  4 int gh(char *str,char *ch,int n) {  5     for(int i=1; i