HDU3336--所以前缀的出现次数和（KMP）
题意：http://acm.hdu.edu.cn/showproblem.php?pid=3336
rt
思路：https://www.cnblogs.com/Tree-dream/p/7443897.html
差不多了，dp只是简化递归而已。
1 #define IOS ios_base::sync_with_stdio(0); cin.tie(0); 2 #include <cstdio>//sprintf islower isupper 3 #include <cstdlib>//malloc exit strcat itoa system("cls") 4 #include <iostream>//pair 5 #include <fstream>//freopen("C:\\Users\\13606\\Desktop\\Input.txt","r",stdin); 6 #include <bitset> 7 //#include <map> 8 //#include<unordered_map> 9 #include <vector> 10 #include <stack> 11 #include <set> 12 #include <string.h>//strstr substr strcat 13 #include <string> 14 #include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9; 15 #include <cmath> 16 #include <deque> 17 #include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less 18 #include <vector>//emplace_back 19 //#include <math.h> 20 #include <cassert> 21 #include <iomanip> 22 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor 23 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare) 24 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation 25 //****************** 26 clock_t __START,__END; 27 double __TOTALTIME; 28 void _MS(){__START=clock();} 29 void _ME(){__END=clock();__TOTALTIME=(double)(__END-__START)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;} 30 //*********************** 31 #define rint register int 32 #define fo(a,b,c) for(rint a=b;a<=c;++a) 33 #define fr(a,b,c) for(rint a=b;a>=c;--a) 34 #define mem(a,b) memset(a,b,sizeof(a)) 35 #define pr printf 36 #define sc scanf 37 #define ls rt<<1 38 #define rs rt<<1|1 39 typedef pair<int,int> PII; 40 typedef vector<int> VI; 41 typedef unsigned long long ull; 42 typedef long long ll; 43 typedef double db; 44 const db E=2.718281828; 45 const db PI=acos(-1.0); 46 const ll INF=(1LL<<60); 47 const int inf=(1<<30); 48 const db ESP=1e-9; 49 const int mod=(int)1e9+7; 50 const int N=(int)1e6+10; 51 52 int Next[N],lenb; 53 char b[N]; 54 55 void set_naxt() //子串的next数组:一个字符串的最长前缀和最长后缀相同的长度 56 { 57 int i=0,j=-1; 58 Next[0]=-1; //初始化为-1，表示不存在相同的最长前缀和最大后缀 59 while(i<lenb) 60 { 61 if(j==-1||b[i]==b[j]) 62 { 63 i++; 64 j++; 65 Next[i]=j; //把j（相同的最大前缀和最大后缀的长）赋值next[i] 66 } 67 else 68 j=Next[j]; //往前回溯 69 } 70 } 71 int dp[N]; 72 73 void solve() 74 { 75 sc("%d",&lenb); 76 sc("%s",b); 77 b[lenb++]='%'; 78 fo(i,0,lenb)dp[i]=0; 79 set_naxt(); 80 int ans=0; 81 for(int i=1;i<lenb;++i) 82 dp[i]=dp[Next[i]]+1,ans+=dp[i],ans%=10007; 83 pr("%d\n",ans); 84 } 85 86 int main() 87 { 88 int T; 89 sc("%d",&T); 90 while(T--)solve(); 91 return 0; 92 } 93 94 /**************************************************************************************/
