[Data structure] Half-Lookup

Half-lookup of data structures

/* Name: Half lookup language: Data Structure C language compiling environment: VC ++ 6.0 Date: */# include <stdio. h> # include <malloc. h> # include <windows. h> # define N 11 // number of data elements typedef int KeyType; // set the keyword field to integer typedef struct // data element type {KeyType key; // The keyword field int others; // other part} ElemType; // Search_Seq.h the sequence storage structure of the static search table. The base address of the data element storage space is typedef struct {// allocated according to the actual length during table creation, element type * elem; int length; // table length} SSTable; ElemType r [N] = }, },{ }}; // Data elements (taking P219 data as an example), basic operations for global variables // static search tables (ordered tables and ordered tables) (7) // construct a static sequence query table ST (data from the Global Array r) int Creat_Seq (SSTable * ST, int n) {int I; (* ST ). elem = (ElemType *) calloc (n + 1, sizeof (ElemType); // dynamically generate n + 1 Data Element space (No unit 0) if (! (* ST ). elem) return 0; for (I = 1; I <= n; I ++) * (* ST ). elem + I) = r [I-1]; // assigns the value of the global array r to ST (* ST) in sequence ). length = n; return 1 ;}// rebuild the static search table to sort the void Ascend (SSTable * ST) by keyword in non-descending order. {int I, j, k; for (I = 1; I <(* ST ). length; I ++) {k = I; (* ST ). elem [0] = (* ST ). elem [I]; // the value to be compared is stored in the Unit [0] for (j = I + 1; j <= (* ST ). length; j ++) // find the smaller I value if (* ST ). elem [j]. key <(* ST ). elem [0]. key) {k = j; (* ST ). elem [0] = (* ST ). elem [j];} if (k! = I) // if there is a smaller value, the {(* ST) is exchanged ). elem [k] = (* ST ). elem [I]; (* ST ). elem [I] = (* ST ). elem [0] ;}}// construct a static search table ST with n data elements in non-descending order of keywords, // data comes from the Global Array r int Creat_Ord (SSTable * ST, int n) {int f; f = Creat_Seq (ST, n); // construct a static table if (f) // If a static table exists, perform Ascend (ST); return f;} // Destroy the table ST int Destroy (SSTable * ST) {free (* ST ). elem); (* ST ). elem = NULL; (* ST ). length = 0; return 1;} // algorithm 9.2 P220 // search for the data element whose keyword is key in the ST segment of the ordered table. If yes, the function // value is the position of the element in the table. Otherwise, the value is 0. Int Search_Bin (SSTable ST, KeyType key) {int low, high, mid; low = 1; // set the initial value of the interval to high = ST. length; while (low <= high) {mid = (low + high)/2; if (key = ST. elem [mid]. key) // find the element to be queried: return mid; else if (key <ST. elem [mid]. key) high = mid-1; // continue searching for elselow = mid + 1 in the First Half; // continue searching in the second half} return 0; // The sequence table does not contain the element to be queried} // the Visit () function is called once and only once for each element of ST in order. Int Traverse (SSTable ST, void (* Visit) (ElemType) {ElemType * p; int I; p = ++ ST. elem; // p points to the first element. The 0th elements are not used for (I = 1; I <= ST. length; I ++) Visit (* p ++); return 1;} void print (ElemType c) // Traverse () the called function {printf ("(% d)", c. key, c. others) ;}int main () {SSTable st; int I; KeyType s; Creat_Ord (& st, N ); // generate a non-descending static search table st Traverse (st, print) from the global array ); // stprintf ("\ n enter the keyword of the value to be searched:"); scanf ("% d", & s ); I = Search_Bin (st, s); // semi-query the ordered table if (I) print (st. elem [I]); elseprintf ("not found. \ n "); Destroy (& st); system (" pause "); return 0;}/* output result: (5 1) (13 2) (19 3) (21 4) (37 5) (56 6) (64 7) (75 8) (80 9) (88 10) (92 11) enter a keyword for the value to be searched: 75 (75 8) press any key to continue... */

The running result is as follows: