loj10043. 「一本通 2.2 例 1」剪花布条

Posted 2020-12-31 junk-yao-blog

思路：
　　简单KMP

#include<cstdio>
#include<iostream>
#include<string>
#include<cstring>
using namespace std;
inline int qread(){
    register int ch = getchar(), x = 0, flag = 0;
    while(ch < ‘0‘ || ch > ‘9‘)    {if(ch == ‘-‘)    flag = 1;    ch = getchar();}
    while(ch >= ‘0‘ && ch <= ‘9‘)    x = 10 * x + ch - 48, ch = getchar();
    return flag ? -x : x;
}
char B[1010], A[1010];
int nxt[1010], M, N;
void findnxt(){
    int j = 0;
    for(int i = 1; i < M; ++i){
        while(j > 0 && B[j + 1] != B[i + 1])    j = nxt[j];
        if(B[j + 1] == B[i + 1])    ++j;
        nxt[i + 1] = j;
    }
}
int KMP(){
    int j = 0, cnt = 0;
    for(int i = 0; i < N; ++i){
        while(j > 0 && B[j + 1] != A[i + 1])    j = nxt[j];
        if(B[j + 1] == A[i + 1])    ++j;
        if(j == M){cnt++;    j = 0;}
    }
    return cnt;
}
int main(void){
    while(1){
        memset(nxt, 0, sizeof(nxt));
        scanf("%s", A + 1);    
        if(A[1] == ‘#‘)    return 0;
        scanf("%s", B + 1);
        N = strlen(A + 1), M = strlen(B + 1);
        findnxt();
        cout << KMP() << endl;
    }
}