0001 int* buildNext ( char* P ) { //构造模式串P的next表
0002    int m = strlen ( P ), j = 0; //“主”串指针
0003    int* next = new int[m]; int t = next[0] = -1; //next表，首项必为-1
0004    while ( j < m - 1 )
0005       if ( 0 > t || P[t] == P[j] ) { //匹配
0006          ++t; ++j; next[j] = t; //则递增赋值：此处可改进...
0007       } else //否则
0008          t = next[t]; //继续尝试下一值得尝试的位置
0009    return next;
0010 }