KMP / hdu 1711 [找到匹配的位置并返回]

kmp 很好，要熟练

#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <cmath>
#include <vector>
#include <stack>
#include <deque>
#include <queue>
#include <bitset>
#include <list>
#include <map>
#include <set>
#include <iterator>
#include <algorithm>
#include <functional>
#include <utility>
#include <sstream>
#include <climits>
#include <cassert>
#define BUG puts("here!!!");

using namespace std;
const int N = 1000005;
const int M = 10005;

int s
;
int t[M];
int next[M];
void getNext(int len) {
int i, j;
i = 0, j = -1;
next[0] = -1;
while(i < len-1) {
if(j == -1 || t[i] == t[j]) {
i++, j++, next[i] = j;
}
else {
j = next[j];
}
}
}
int kmp(int sl, int tl) {
int i = 0, j = 0;
while(i < sl && j < tl) {
if(j == -1 || s[i] == t[j]) {
i++, j++;
}
else j = next[j];
}
if(j == tl) return i-j+1;
else return -1;
}
// abcabcababcabcabdef
// abcabcabd
int main() {
int T, n, m, ans;
cin >> T;
while(T--) {
cin >> n >> m;
for(int i = 0; i < n; i++) {
scanf("%d", s+i);
}
for(int i = 0; i < m; i++) {
scanf("%d", t+i);
}
getNext(m);
ans = kmp(n, m);
cout << ans << endl;
}
return 0;
}

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