Example of the shortest path query in c ++

This article describes how to query the Shortest Path in c ++. For more information, see

The Code is as follows:

// Shortest_path.c

# Include

# Include // use file

# Include // available gets (), puts ()

# Include "shortest_path.h"

# Deprecision MAX 32767

# Define MENU "welcome to the navigation system! \ N ============ menu =================\ n0, load map \ n1, create map \ n2, query shortest path \ n3, exit \ n ========== menu ===========\ n"

Struct stmap map; // undirected network

Const char * filepath1 = "D: \ spots. dat ";

Const char * filepath2 = "D: \ paths. dat ";

Int load1 ()

{

FILE * fp;

Int I;

Fp = fopen (filepath1, "r ");

If (fp = NULL) {printf ("spots file opening exception, read failed"); return-1 ;}

Fread (& map. spotnum, sizeof (int), 1, fp );

For (I = 0; I

{

Fread (map. spot [I]. name, sizeof (char), 10, fp );

Fread (map. spot [I]. intro, sizeof (char), 20, fp );

}

Fclose (fp );

Return 0;

}

Int load2 ()

{

FILE * fp;

Int I, j;

Fp = fopen (filepath2, "r ");

If (fp = NULL) {printf ("abnormal opening of the paths file, failed to read"); return-1 ;}

Fread (& map. pathmatrix, sizeof (int), 1, fp );

For (I = 0; I

For (j = 0; j

Fread (& map. pathmatrix [I] [j], sizeof (int), 1, fp );

Fclose (fp );

Return 0;

}

Void loadmap ()

{

If (load1 () = 0)

Printf ("spot read succeeded \ n ");

Else

Printf ("failed to read spot \ n ");

If (load2 () = 0)

Printf ("path read successfully \ n ");

Else

Printf ("path failed to read \ n ");

}

Void drawmap () // input directly

{

Int I;

Int a, B;

Char s1 [10], s2 [10];

Printf ("How many scenic spots are there? (<= 20) "); // map. spotmun

Fflush (stdin );

Scanf ("% d", & map. spotnum );

Printf ("How many scenic spots are directly connected to each other? "); // Map. pathnum

Fflush (stdin); // clear the Keyboard Buffer, in "stdio. h"

Scanf ("% d", & map. pathnum );

For (a = 0;

For (B = 0; B

{

If (a = B) map. pathmatrix [a] [B] = 0;

Else map. pathmatrix [a] [B] = MAX;

}

For (I = 0; I

Printf ("enter the name of the % d scenic spot (<= 10 letters)", I + 1 );

Fflush (stdin );

Gets (map. spot [I]. name );

Printf ("enter an introduction to the % d scenic spots (<= 20 letters)", I + 1 );

Fflush (stdin );

Gets (map. spot [I]. intro );

} // Enter the Scenic spot name and description map. spot []. name; map. spot []. intro

For (I = 0; I

Do {

Printf ("Enter the starting point of PATH % d", I + 1 );

Fflush (stdin );

Gets (s1 );

For (a = 0;

If (! Strcmp (map. spot [a]. name, s1) break; // find the scenic spot number

If (a = map. spotnum) printf ("this attraction does not exist. Please enter it again. \ N ");

} While (a = map. spotnum );

Do {

Printf ("Enter the end point of PATH % d", I + 1 );

Fflush (stdin );

Gets (s2 );

For (B = 0; B

If (! Strcmp (map. spot [B]. name, s2) break;

If (B = map. spotnum) printf ("this attraction does not exist. Please enter it again. \ N ");

} While (B = map. spotnum );

Printf ("Enter the length of PATH % d", I + 1 );

Fflush (stdin );

Scanf ("% d", & map. pathmatrix [a] [B]);

Map. pathmatrix [B] [a] = map. pathmatrix [a] [B]; // input path length

}

}

Void shortestpath () // shortest path, which is used to input the output path and distance from the start point.

{

Struct stspath spath [20];

Int s, t, v, w, min;

Char s1 [10], s2 [10];

Int pathorder [20];

Struct stspath * p; // pathorder

Do {

Printf ("Enter the Starting Point"); // you can specify the starting point.

Fflush (stdin );

Gets (s1 );

For (s = 0; s

If (! Strcmp (map. spot [s]. name, s1) break;

If (s = map. spotnum) printf ("this attraction does not exist. Please enter it again. \ N ");

} While (s = map. spotnum );

Do {

Printf ("Enter the destination"); // find the destination scenic spot number

Fflush (stdin );

Gets (s2 );

For (t = 0; t

If (! Strcmp (map. spot [t]. name, s2) break;

If (t = map. spotnum) printf ("this attraction does not exist. Please enter it again. \ N ");

} While (t = map. spotnum );

For (v = 0; v

{

Spath [v]. length = MAX;

Spath [v]. in = 0;

}

Spath [s]. in = 1;

Spath [s]. length = 0;

Spath [s]. pior = NULL;

V = s;

While (v! = T ){

For (w = 0; w

If ((! Spath [w]. in) & (spath [w]. length> spath [v]. length + map. pathmatrix [v] [w]) {

Spath [w]. length = spath [v]. length + map. pathmatrix [v] [w];

Spath [w]. pior = & spath [v];

}

Min = MAX;

For (w = 0; w

If ((! Spath [w]. in) & (spath [w]. length

Min = spath [w]. length;

V = w;

}

Spath [v]. in = 1;

}

Printf ("Shortest path length: % d, shortest path: \ n", spath [t]. length); // print path

For (v = 0, p = & spath [t]; p-> pior! = NULL; p = p-> pior)

{

Pathorder [v] = p-spath;

V ++;

}

Pathorder [v] = s;

For (; v> = 0; v --)

Printf ("% 10 s", map. spot [pathorder [v]. name );

}

Void main ()

{

Int menu = 1;

Printf (MENU );

While (menu! = 3)

{

Printf ("\ n Please enter your option (number) \ n ");

Fflush (stdin );

Scanf ("% d", & menu );

Switch (menu)

{

Case 0: loadmap (); printf ("\ n \ n"); break;

Case 1: drawmap (); printf ("\ n created \ n"); break;

Case 2: shortestpath (); printf ("\ n query completed \ n"); break;

}

}

Printf ("Thank you! ");

}

2. [file] shortest_path.h ~ 430B download (2)

# Ifndef _ SHORTEST_PATH_H _

# Define _ SHORTEST_PATH_H _

Struct stspot {// vertex of a scenic spot

Char name [11]; // scenic spot name no more than 10

Char intro [20]; // no more than 20

};

Struct stmap {// The entire undirected network

Stspot spot [20]; // point, scenic spot Vector

Int pathmatrix [20] [20]; // edge, the adjacent matrix of the path

Int spotnum;

Int pathnum;

};

Struct stspath // list of scenic spots when finding the Shortest Path

{

Stspath * pior;

Int in; // can be boolen

Int length;

};

# Endif

Note: For more exciting articles, please pay attention to the Programming Tutorial section of the Helper house.