delete pics to save space

7.3974.cpp

@@ -0,0 +1,51 @@
+#include<cstdio>
+#include<cstring>
+#include<algorithm>
+using namespace std;
+const int maxn=1000005;
+const int P=13141;
+char s[maxn],rs[maxn];
+int n,kase;
+unsigned long long H[maxn],RH[maxn],pm[maxn];
+int solve()
+{
+	n=strlen(s+1);
+	memcpy(rs,s,n+1);
+	reverse(rs+1,rs+1+n);
+	for(int i=1;i<=n;i++) H[i]=H[i-1]*P+(s[i]-'a'+1);
+	for(int i=1;i<=n;i++) RH[i]=RH[i-1]*P+(rs[i]-'a'+1);
+	int res=0;
+	for(int i=1,ri=n;i<=n;i++,ri--) // <20><><EFBFBD><EFBFBD>Ϊ<EFBFBD><CEAA><EFBFBD><EFBFBD>,<2C><>s[i]Ϊ<><CEAA><EFBFBD><EFBFBD>
+	{
+		int L=0,R=min(i-1,n-i),M,now=0;
+		while(L<=R)
+		{
+			M=(L+R)>>1;
+			if(H[i-1]-H[i-1-M]*pm[M]==RH[ri-1]-RH[ri-1-M]*pm[M]) L=M+1,now=M;
+			else R=M-1;
+		}
+		res=max(res,now*2+1);
+	}
+	for(int i=2,ri=n-1;i<=n;i++,ri--) // <20><><EFBFBD><EFBFBD>Ϊż<CEAA><C5BC>,<2C><>s[i-1]<5D><>s[i]Ϊ<><CEAA><EFBFBD><EFBFBD>
+	{
+		int L=0,R=min(i-1,n-i+1),M,now=0;
+		while(L<=R)
+		{
+			M=(L+R)>>1;
+			if(H[i-1]-H[i-1-M]*pm[M]==RH[ri]-RH[ri-M]*pm[M]) L=M+1,now=M;
+			else R=M-1;
+		}
+		res=max(res,now*2);
+	}
+	return res;
+}
+int main()
+{
+#ifdef local
+	freopen("pro.in","r",stdin);
+#endif
+	pm[0]=1;
+	for(int i=1;i<=1000000;i++) pm[i]=pm[i-1]*P;
+	while(scanf("%s",s+1),strcmp(s+1,"END")) printf("Case %d: %d\n",++kase,solve());
+	return 0;
+}