AtCoder Regular Contest 069 D

D - Menagerie

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 si. Here, if si is o, the animal said that the two neighboring animals are of the same species, and if si 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.

Input

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

N

s

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 ti is S, it indicates that the animal numbered i is a sheep. If ti is W, it indicates that the animal numbered i is a wolf.

Sample Input 1

Copy

6

ooxoox

Sample Output 1

Copy

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.

b34c052fc21c42d2def9b98d6dccd05c.png

Sample Input 2

Copy

3

oox

Sample Output 2

Copy

-1

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

Sample Input 3

Copy

10

oxooxoxoox

Sample Output 3

Copy

SSWWSSSWWS

大型模拟

#include <bits/stdc++.h>
using namespace std;
const int N=123456;
int gh(char *str,char *ch,int n) {
for(int i=1; i<n; i++) {
if(i<n-2) {
if(str[i]=='o') {
if(ch[i]=='S') {
ch[i+1]=ch[i-1];
} else {
if(ch[i-1]=='S') ch[i+1]='W';
else ch[i+1]='S';
}
} else {
if(ch[i]=='S') {
if(ch[i-1]=='S') ch[i+1]='W';
else ch[i+1]='S';
} else {
ch[i+1]=ch[i-1];
}
}
}
else if(i==n-2) {
if(str[i]=='o') {
if(ch[i]=='S') {
if(ch[i+1]!=ch[i-1]) {
return 1;
}
}
else {
if(ch[i+1]==ch[i-1]){
return 1;
}
}
}
else{
if(ch[i]=='S'){
if(ch[i+1]==ch[i-1]){
return 1;
}
}
else{
if(ch[i+1]!=ch[i-1]) {
return 1;
}
}
}
}
else if(i==n-1){
if(str[i]=='x'){
if(ch[i]=='S') {
if(ch[n-2]==ch[0]) return 1;
}
else{
if(ch[n-2]!=ch[0]) return 1;
}
}
else{
if(ch[i]=='S'){
if(ch[n-2]!=ch[0]) return 1;
}
else{
if(ch[n-2]==ch[0]) return 1;
}
}
}
}
return 0;
}
int main() {
char str
;
char ch
;
int n;
int flag=0;
scanf("%d",&n);
scanf("%s",str);
ch[0]='S';
if(str[0]=='o') {
memset(ch,0,sizeof(ch));
ch[0]='S';
ch[1]='S';
ch[n-1]='S';
flag=gh(str,ch,n);
if(flag==0) {
for(int i=0; i<n; i++) printf("%c",ch[i]);
puts("");
return 0;
} else {
memset(ch,0,sizeof(ch));
ch[0]='S';
ch[1]='W';
ch[n-1]='W';
flag=gh(str,ch,n);
if(flag==0){
for(int i=0;i<n;i++) printf("%c",ch[i]);
puts("");
return 0;
}
}
}
else{
memset(ch,0,sizeof(ch));
ch[0]='S';
ch[1]='S';
ch[n-1]='W';
flag=gh(str,ch,n);
if(flag==0){
for(int i=0;i<n;i++) printf("%c",ch[i]);
puts("");
return 0;
}
else{
memset(ch,0,sizeof(ch));
ch[0]='S';
ch[1]='W';
ch[n-1]='S';
flag=gh(str,ch,n);
if(flag==0){
for(int i=0;i<n;i++) printf("%c",ch[i]);
puts("");
return 0;
}
}
}
ch[0]='W';
if(str[0]=='o'){
memset(ch,0,sizeof(ch));
ch[0]='W';
ch[1]='S';
ch[n-1]='W';
flag=gh(str,ch,n);
if(flag==0){
for(int i=0;i<n;i++) printf("%c",ch[i]);
puts("");
return 0;
}
else{
ch[0]='W';
ch[1]='W';
ch[n-1]='S';
flag=gh(str,ch,n);
if(flag==0){
for(int i=0;i<n;i++) printf("%c",ch[i]);
puts("");
return 0;
}
}
}
else{
memset(ch,0,sizeof(ch));
ch[0]='W';
ch[1]='S';
ch[n-1]='S';
flag=gh(str,ch,n);
if(flag==0){
for(int i=0;i<n;i++) printf("%c",ch[i]);
puts("");
}
else{
ch[0]='W';
ch[1]='W';
ch[n-1]='W';
flag=gh(str,ch,n);
if(flag==0){
for(int i=0;i<n;i++) printf("%c",ch[i]);
puts("");
return 0;
}
}
}
puts("-1");
return 0;
}