#include <stdio.h> #include <stdlib.h> #include <string.h> #define N 100 void cal_next( char * str, int * next, int len ) { int i, j; next[0] = -1; for( i = 1; i < len; i++ ) { j = next[ i - 1 ]; while( str[ j + 1 ] != str[ i ] && ( j >= 0 ) ) { j = next[ j ]; } if( str[ i ] == str[ j + 1 ] ) { next[ i ] = j + 1; } else { next[ i ] = -1; } } } int KMP( char * str, int slen, char * ptr, int plen, int * next ) { int s_i = 0, p_i = 0; while( s_i < slen && p_i < plen ) { if( str[ s_i ] == ptr[ p_i ] ) { s_i++; p_i++; } else { if( p_i == 0 ) { s_i++; } else { p_i = next[ p_i - 1 ] + 1; } } } return ( p_i == plen ) ? ( s_i - plen ) : -1; } int main() { char str[ N ] = {0}; char ptr[ N ] = {0}; int slen, plen; int next[ N ]; while( scanf( "%s%s", str, ptr ) ) { slen = strlen( str ); plen = strlen( ptr ); cal_next( ptr, next, plen ); printf( "%d\n", KMP( str, slen, ptr, plen, next ) ); } return 0; }
