codeforces 305E Playing with String

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<algorithm>
 6 #define maxn 5005
 7 using namespace std;
 8 char ch,s[maxn];
 9 int n,sg[maxn],l,idx,tmp;
10 struct DATA{
11     int l,r,siz;
12 }list[maxn];
13 bool ok,bo[maxn],can[maxn],flag;
14 void read(int &x){
15     for (ok=0,ch=getchar();!isdigit(ch);ch=getchar()) if (ch==‘-‘) ok=1;
16     for (x=0;isdigit(ch);x=x*10+ch-‘0‘,ch=getchar());
17     if (ok) x=-x;
18 }
19 void calc(int k){
20     for (int i=1,t1,t2;i<=k;i++){
21         t1=(i-1)-1,t2=k-(i+1);
22         if (t1>0&&sg[t1]==-1) calc(t1);
23         if (t2>0&&sg[t2]==-1) calc(t2);
24     }
25     memset(bo,0,sizeof(bo));
26     for (int i=1,t,t1,t2;i<=k;i++){
27         t1=(i-1)-1,t2=k-(i+1),t=0;
28         if (t1>0) t^=sg[t1];
29         if (t2>0) t^=sg[t2];
30         bo[t]=1;
31     }
32     for (int i=0;;i++) if (!bo[i]){sg[k]=i;break;}
33 }
34 int main(){
35     scanf("%s",s+1);
36     n=strlen(s+1);
37     for (int i=2;i<n;i++) if (s[i-1]==s[i+1]) can[i]=1;
38     for (int i=2;i<n;i++){
39         if (can[i]&&!l) l=i;
40         if (!can[i]&&l) list[++idx]=(DATA){l,i-1,i-1-l+1},l=0;
41     }
42     if (l) list[++idx]=(DATA){l,n-1,n-1-l+1};
43     memset(sg,-1,sizeof(sg));
44     for (int i=1;i<=idx;i++){
45         if (sg[list[i].siz]==-1) calc(list[i].siz);
46         tmp^=sg[list[i].siz];
47     }
48     if (tmp){
49         puts("First");
50         for (int i=1,t;i<=idx;i++){
51             t=sg[list[i].siz];
52             for (int j=list[i].l,t1,t2,t3;j<=list[i].r;j++){
53                 t1=(j-1)-list[i].l,t2=list[i].r-(j+1),t3=0;
54                 if (t1>0) t3^=sg[t1];
55                 if (t2>0) t3^=sg[t2];
56                 if (!(tmp^t^t3)){printf("%d\n",j),flag=1;break;}
57             }
58             if (flag) break;
59         }
60     }
61     else puts("Second");
62     return 0;
63 }