CUBE-091: Mini Contest

#include <bits/stdc++.h>
using namespace std;
char ar[100010];
void BB_WW_even(int x,int y,char ch){
    int c=1;
    for(int i=x+1;i<y;i++){
        if((c%2==1&&ch=='W')||(c%2==0&&ch=='B')) ar[i]='B';
        else ar[i]='W';
        c++;
    }
}
void BB_WW_odd(int x,int y,char ch){
    int c=1;
    for(int i=x+1;i<y-1;i++){
        if((c%2==1&&ch=='W')||(c%2==0&&ch=='B')) ar[i]='B';
        else ar[i]='W';
        c++;
    }
    ar[y-1]='G';
}

int main(){

    int n,x=0,y=0;
    bool have;
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf(" %c",&ar[i]);
        if(ar[i]=='X') have=true;
        else y=i;
        if((x!=0 || y!=0) && x!=y){
            //printf("%d %d\n",x,y);
            if(x==0 && y!=x+1 && (y-x)%2==1)
                BB_WW_even(x,y,(ar[y]=='B')? 'W':'B');
            else if(x==0 && y!=x+1 && (y-x)%2==0)
                BB_WW_even(x,y,ar[i]);
            else if(ar[x]==ar[y] && y!=x+1 && (y-x)%2==0) BB_WW_even(x,y,ar[x]);
            else if(ar[x]==ar[y] && y!=x+1 && (y-x)%2==1) BB_WW_odd(x,y,ar[x]);
            else if(ar[x]!=ar[y] && y!=x+1 && (y-x)%2==1) BB_WW_even(x,y,ar[x]);
            else if(ar[x]!=ar[y] && y!=x+1 && (y-x)%2==0) BB_WW_odd(x,y,ar[x]);
        }
        x=y;
    }

    if(have && x==0 &&y==0){
        for(int i=1;i<=n;i++) {
            if(i%2==0) printf("W");
            else printf("B");
        }
        return 0;
    }

    for(int i=1;i<=n;i++){
        if(ar[i]=='X'){
            BB_WW_even(i-1,n+1,ar[i-1]);
        }
        printf("%c",ar[i]);
    }
    return 0;
}