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Commit 0f90525

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Removed unnecessary comments + improved variable names + added new comments
1 parent 1782eea commit 0f90525

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1 file changed

+91
-153
lines changed

1 file changed

+91
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‎src/Algorithms/biDirectionalBfs.js

Lines changed: 91 additions & 153 deletions
Original file line numberDiff line numberDiff line change
@@ -2,168 +2,107 @@ import React from 'react'
22
import bfs from './bfs'
33
import { getAllNodes } from './Dijkstra';
44

5-
export function biDirectionalBfs(grid,start,finish) {
6-
let queueSt = [];
7-
let queueBk = [];
8-
const allnodes = getAllNodes(grid);
9-
// const visitedNodes = [];
10-
11-
queueSt.push(start);
12-
queueBk.push(finish);
13-
start.isVisited=true;
14-
finish.isVisited=true;
15-
let neighbors=[];
16-
let short=[]
17-
let shortBk=[]
18-
let st=[]
19-
let bk = []
5+
export function biDirectionalBfs(grid, start, finish) {
6+
let queueForward = []; /* queue that stores nodes to be visited next in forward dir */
7+
let queueBackward = []; /* queue that stores nodes to be visited next in backword dir */
8+
const allnodes = getAllNodes(grid); /* get all nodes coordinates from gird */
9+
10+
11+
/* push the start node in forward queue & finish node in backward queue */
12+
queueForward.push(start);
13+
queueBackward.push(finish);
14+
15+
/* mark the start node & finish node as visited */
16+
start.isVisited = true;
17+
finish.isVisited = true;
18+
19+
20+
let neighbors = []; // to store neighbours of current node
21+
22+
let curForwardLevelNodes = [];
23+
let curBackwardLevelNodes = [];
24+
25+
let visitedForward = [];
26+
let visitedBackward = [];
27+
2028
let s1;
2129
let s2;
30+
2231
neighbors.push(start);
2332
neighbors.push(finish);
24-
let neighborsUnvis=[];
25-
26-
// short.push(start);
27-
// shortBk.push(finish);
28-
29-
while(queueSt !==[] && queueBk!==[]){
30-
31-
const currentSt = queueSt.shift();
32-
const currentBk = queueBk.shift();
33-
const neighSt = getUnvisitedNeighboursBbfs(currentSt,grid);
34-
const neighBk = getUnvisitedNeighboursBbfs(currentBk,grid);
35-
36-
short=[]
37-
shortBk=[]
38-
39-
// if(neighSt!= null){
40-
updateUnvisitedNeighbors(currentSt,grid);
41-
// }
42-
// if( neighBk!=null){
43-
updateUnvisitedNeighbors(currentBk,grid);
44-
// }
45-
46-
console.log(neighSt);
47-
console.log(neighBk);
48-
49-
50-
51-
for(let i=0;i<neighSt.length || i<neighBk.length;i++){
52-
53-
console.log(neighBk[i],neighSt[i]);
54-
55-
if(i<neighSt.length ){
56-
// for(let j=0;j<neighbors.length;j++){
57-
// if(neighSt[i].row === neighbors[j].row && neighSt[i].col === neighbors[j].col){
58-
let sur = getSurroundings(neighSt[i],grid);
59-
for (let j=0;j<sur.length;j++){
60-
if(bk.includes(sur[j])){
61-
let r2;
62-
console.log("end ",sur[j]);
63-
neighSt[i].isVisited=true
64-
// let val = neighSt[i]
65-
// // while(!grid[val.row][val.col-1].isBbfs || !grid[val.row+1][val.col].isBbfs || !grid[val.row-1][val.col].isBbfs){
66-
// // val= val.previousNode
67-
// // }
68-
// if(start.row===val.row){
69-
// while(!grid[val.row][val.col-1].isBbfs){
70-
// val = val.previousNode
71-
// }
72-
// r2 = grid[val.row][val.col-1]
73-
// }
74-
// else if(start.col>val.col){
75-
// while(!grid[val.row+1][val.col].isBbfs){
76-
// val = val.previousNode
77-
// }
78-
// r2 = grid[val.row+1][val.col]
79-
// }
80-
// else if(start.col<val.col){
81-
// while(!grid[val.row-1][val.col].isBbfs){
82-
// val = val.previousNode
83-
// }
84-
// r2 = grid[val.row-1][val.col]
85-
// }
86-
// console.log(neighSt[i].row);
87-
88-
return [neighbors,neighSt[i],sur[j]];
89-
}
33+
34+
let neighborsUnvis = [];
35+
36+
while (queueForward !== [] && queueBackward !== []) {
37+
38+
const currentForwardNode = queueForward.shift(); /* shift() -> pops & returns front node in queue*/
39+
const currentBackwardNode = queueBackward.shift();
40+
41+
const neighsForward = getUnvisitedNeighboursBbfs(currentForwardNode, grid);
42+
const neighsBackward = getUnvisitedNeighboursBbfs(currentBackwardNode, grid);
43+
44+
curForwardLevelNodes = [];
45+
curBackwardLevelNodes = [];
46+
47+
updateUnvisitedNeighbors(currentForwardNode, grid);
48+
updateUnvisitedNeighbors(currentBackwardNode, grid);
49+
50+
for (let i = 0; i < neighsForward.length || i < neighsBackward.length; i++) {
51+
52+
// visits all the currentForwardNodes neighbours, if any
53+
if (i < neighsForward.length) {
54+
55+
let sur = getSurroundings(neighsForward[i], grid);
56+
for (let j = 0; j < sur.length; j++) {
57+
58+
// if forward nodes meet backward nodes, the we found a path & return it
59+
if (visitedBackward.includes(sur[j])) {
60+
neighsForward[i].isVisited = true;
61+
return [neighbors, neighsForward[i], sur[j]];
9062
}
91-
92-
93-
console.log(neighSt[i])
94-
neighSt[i].isVisited = true;
95-
neighSt[i].isBbfs = true;
96-
queueSt.push(neighSt[i]);
97-
st.push(neighSt[i]);
98-
short.push(neighSt[i]);
9963
}
10064

101-
if(i<neighBk.length){
102-
// for(let j=0;j<neighbors.length;j++){
103-
// if(neighSt[i].row === neighbors[j].row && neighSt[i].col === neighbors[j].col){
104-
let sur = getSurroundings(neighBk[i],grid);
105-
for (let j=0;j<sur.length;j++){
106-
if(st.includes(sur[j])){
107-
let r2;
108-
console.log("end--",sur[j]);
109-
neighBk[i].isVisited=true
110-
// let val = neighBk[i]
111-
// while(!grid[val.row][val.col-1].isBbfs || !grid[val.row+1][val.col].isBbfs || !grid[val.row-1][val.col].isBbfs){
112-
// val= val.previousNode
113-
// }
114-
// if(start.row===val.row){
115-
// while(!grid[val.row][val.col-1].isBbfs){
116-
// val = val.previousNode
117-
// }
118-
// r2 = grid[val.row][val.col-1]
119-
// }
120-
// else if(start.col>val.col){
121-
// while(!grid[val.row+1][val.col].isBbfs){
122-
// val = val.previousNode
123-
// }
124-
// r2 = grid[val.row+1][val.col]
125-
// }
126-
// else if(start.col<val.col){
127-
// while(!grid[val.row-1][val.col].isBbfs){
128-
// val = val.previousNode
129-
// }
130-
// r2 = grid[val.row-1][val.col]
131-
// }
132-
// console.log(neighBk[i]);
133-
return [neighbors,neighBk[i],sur[j]];
134-
}
65+
neighsForward[i].isVisited = true;
66+
neighsForward[i].isBbfs = true;
67+
68+
queueForward.push(neighsForward[i]);
69+
70+
visitedForward.push(neighsForward[i]);
71+
curForwardLevelNodes.push(neighsForward[i]);
13572
}
136-
137-
console.log(neighBk[i])
138-
neighBk[i].isVisited = true;
139-
neighBk[i].isBbfs = true;
140-
queueBk.push(neighBk[i]);
141-
bk.push(neighBk[i])
142-
shortBk.push(neighBk[i]);
143-
144-
145-
73+
74+
// visits all the currentBackwardNodes neighbours, if any
75+
if (i < neighsBackward.length) {
76+
let sur = getSurroundings(neighsBackward[i], grid);
77+
for (let j = 0; j < sur.length; j++) {
78+
79+
// if forward nodes meet backward nodes, the we found a path & return it
80+
if (visitedForward.includes(sur[j])) {
81+
neighsBackward[i].isVisited = true
82+
return [neighbors, neighsBackward[i], sur[j]];
83+
}
14684
}
14785

148-
// console.log(neighSt[i]);
149-
// if(neighBk[i] in neighbors){
150-
// return [neighbors,neighBk[i]]
151-
// }
86+
neighsBackward[i].isVisited = true;
87+
neighsBackward[i].isBbfs = true;
88+
89+
queueBackward.push(neighsBackward[i]);
90+
91+
visitedBackward.push(neighsBackward[i])
92+
curBackwardLevelNodes.push(neighsBackward[i]);
93+
94+
}
15295
}
153-
neighbors = [...neighbors,...short,...shortBk]
96+
neighbors = [...neighbors,...curForwardLevelNodes,...curBackwardLevelNodes]
15497
}
15598
}
15699

157100
function updateUnvisitedNeighbors(node, grid) {
158101
/** Updates the distances of unvisited nodes */
159102
const unvisitedNeighbors = getUnvisitedNeighboursBbfs(node, grid);
160-
console.log("unvis")
161-
console.log(unvisitedNeighbors);
162-
// if(unvisitedNeighbors !== undefined){
103+
163104
for (const neighbor of unvisitedNeighbors) {
164-
165-
neighbor.previousNode = node;
166-
105+
neighbor.previousNode = node;
167106
}
168107

169108
}
@@ -178,24 +117,23 @@ function getUnvisitedNeighboursBbfs(node, grid) {
178117
if (col > 0) neighbors.push(grid[row][col - 1]);
179118
if (col < grid[0].length - 1) neighbors.push(grid[row][col + 1]);
180119
return neighbors.filter(neighbor => !neighbor.isVisited);
181-
182-
}
120+
121+
}
183122

184123

185124

186125
export function getNodesInShortestPathOrderBbfs(edNode) {
187126
/** Backtracking alogirthm to get the path from Finish node to Start node (or vice versa) */
188-
const nodesInShortestPathOrder = [];
127+
const nodesInShortestPathOrderBbfs = [];
189128
let currentNode = edNode;
190129
while (currentNode != null) {
191-
nodesInShortestPathOrder.unshift(currentNode);
192-
currentNode = currentNode.previousNode;
193-
console.log(currentNode)
130+
nodesInShortestPathOrderBbfs.unshift(currentNode);
131+
currentNode = currentNode.previousNode;
194132
}
195-
return nodesInShortestPathOrder;
133+
return nodesInShortestPathOrderBbfs;
196134
}
197135

198-
function getSurroundings(node,grid){
136+
function getSurroundings(node,grid){
199137
const neighbors = [];
200138
const col = node.col;
201139
const row = node.row;
@@ -205,4 +143,4 @@ function getSurroundings(node,grid){
205143
if (col < grid[0].length - 1) neighbors.push(grid[row][col + 1]);
206144

207145
return neighbors;
208-
}
146+
}

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