Dijstra algorithm to find the shortest distance from the source point to each vertex

The 1:dijstra algorithm often asks for the shortest distance,

Dijstra each time never found node n[], found the shortest point from the source node m, the shortest node, the M is added to the discovered node y[], with the node m to update the other nodes n[]-m the shortest distance . Until all nodes are found

Proof: M is the shortest distance from the source point S,

Because the node is the shortest distance in the discovery node, there is no distance from S to n[]-m to M and less than S to M.

In the discovered node y[], from S to y[] to M distance and, if there is less than s to M distance, then in the shortest distance to obtain s>y[i], it has been used (S>y[i]) + (Y[I]>M) to replace the distance of s>m. So there's no such situation.

Code:

 PackageCom.li.chapter24.mydijstra;ImportJava.io.InputStream;ImportJava.util.Scanner;/*** @program: Gradletestusesubmodule *@author: Yafei Li * @create: 2018-06-28 19:45 * Write your own Dijkstra algorithm to solve the graph theory and its Application 1.4 section A to B shortest path problem **/ Public classMydijstraalgorithm { Public Static voidMain (string[] args) {mydijstraalgorithm dijstraalgorithm=NewMydijstraalgorithm (); int[] Mindisarr = Dijstraalgorithm.dijstra (0);  for(inti = 0; i < mindisarr.length; i++) {System.out.println (mindisarr[i]); }}//vertx The source point of the input Public int[] Dijstra (intvertx) {        int[] arrweight=getarrofgraph (); int[] Arrvertx = Arrweight[vertx];//Other nodes andDistance to Vertx        Boolean[] Isfound =New Boolean[Arrvertx.length]; ISFOUND[VERTX]=true;         for(inti = 0; i < arrvertx.length; i++) {//Traverse all the points            intmindis=Integer.max_value; intv=Vertx;  for(intj = 0; J < Arrvertx.length; J + +) {                if(!Isfound[j]) {                    if(Mindis >Arrvertx[j]) {Mindis=Arrvertx[j]; V=J; }}} Isfound[v]=true;  for(intj = 0; J < Arrvertx.length; J + +) {                if(!Isfound[j]) {                    if(Mindis + arrweight[v][j] < Arrvertx[j]) {//distance from Vertx to V plus distance from V to JArrvertx[j]=mindis +Arrweight[v][j]; }                }            }        }        returnArrvertx; }     Public int[] Getarrofgraph () {Class clazz= This. GetClass (); InputStream ins= Clazz.getresourceasstream ("/data2.txt"); Scanner Scanner=NewScanner (INS); int[] Intarr =New int[8] [8]; intRow=0;  while(Scanner.hasnextline ()) {String line=Scanner.nextline (); String[] Strarr= Line.split ("");  for(inti = 0; i < strarr.length; i++) {Intarr[row][i]=Integer.parseint (Strarr[i]); } row++; }        returnintarr; }}

Below is the data, put under the resource

The following data indicates that the row number, the column number represents the node, and the node is 0-7

Where 8 represents a distance of 8 for the No. 0 node to the 4th node

999 means that there are no neighbors between the two nodes, indicating their distance infinity

8 999 1 9992 0 1 999 6 999 999 999999 1 0 9 4 3 999 999999 999 9 0 999 6 999 28 6 4 999 0 2 7 2999 999 3 6 2 0 999 41 999 999 999 7 999 0 9999 999 999 2 2 4 9 0

Dijstra algorithm to find the shortest distance from the source point to each vertex