Number Sequence
Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 29634 Accepted Submission(s): 12464
Problem Description
Given two sequences of numbers : a[1], a[2], ...... , a[N], and b[1], b[2], ...... , b[M] (1 <= M <= 10000, 1 <= N <= 1000000). Your task is to find a number K which make a[K] = b[1], a[K + 1] = b[2], ...... , a[K + M - 1] = b[M]. If there are more than one K exist, output the smallest one.
Input
The first line of input is a number T which indicate the number of cases. Each case contains three lines. The first line is two numbers N and M (1 <= M <= 10000, 1 <= N <= 1000000). The second line contains N integers which indicate a[1], a[2], ...... , a[N]. The third line contains M integers which indicate b[1], b[2], ...... , b[M]. All integers are in the range of [-1000000, 1000000].
Output
For each test case, you should output one line which only contain K described above. If no such K exists, output -1 instead.
Sample Input
2 13 5 1 2 1 2 3 1 2 3 1 3 2 1 2 1 2 3 1 3 13 5 1 2 1 2 3 1 2 3 1 3 2 1 2 1 2 3 2 1
Sample Output
6 -1
Source
返回匹配到的第一个字母的位置
#include <iostream> #include <cmath> #include <algorithm> #include <cstdio> #include <stdlib.h> #include <string> #include <cstring> #include <map> #include <set> #include <queue> #include <stack> #define INF 0x3f3f3f3f #define ms(x,y) memset(x,y,sizeof(x)) using namespace std; typedef long long ll; const double pi = acos(-1.0); const int mod = 1e9 + 7; const int maxn = 1e5 + 10; int nextval[1000010]; int s[1000010], p[10010]; int slen, plen; //p为模式串 void getnext(int p[], int nextval[]) //朴素kmp,nextval[i]即为1~i-1的最长前后缀长度 { int len = plen; int i = 0, j = -1; nextval[0] = -1; while (i < len) { if (j == -1 || p[i] == p[j]) { nextval[++i] = ++j; } else j = nextval[j]; } } //在s中找p出现的位置 int KMP(int s[], int p[], int nextval[]) { getnext(p, nextval); int ans = 0; int i = 0; //s下标 int j = 0; //p下标 int s_len = slen; int p_len = plen; while (i < s_len && j < p_len) { if (j == -1 || s[i] == p[j]) { i++; j++; } else j = nextval[j]; if (j == p_len) { return i - j + 1; } } return -1; } int main() { //freopen("in.txt","r",stdin); //freopen("out.txt","w",stdout); int t; scanf("%d", &t); while (t--) { scanf("%d%d", &slen, &plen); for (int i = 0; i < slen; i++) scanf(" %d", &s[i]); for (int i = 0; i < plen ; i++) scanf(" %d", &p[i]); printf("%d\n", KMP(s, p, nextval)); } return 0; }