Merge pull request avinashkranjan#499 from SpecTEviL/Shortest-Path-finder-GSSoC'21

Added the Shortest Path Finder gssoc'21

Author: avinashkranjan

Shortest-Path-Finder (GUI)/1. Marked Start and End Point.png

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+# Shortest Path Finder (GUI)
+
+ Shortest Path finder is a GUI application which finds the shortest possible path between two points placed by the user on the board. The shortest path is marked with "Purple" colour. The program also shows the area of the board tracked by the algorithm in "Red" colour to find the shortest path. The "Green" border represents the border of the area tracked. The user can create obstacles simply by clicking on the cell on the board which is represented by "Black" colour. The start point is marked with "Yellow" colour and the end point is marked with "Sky Blue" colour.
+
+## Setup instructions
+
+In order to run this script, You just need the following modules:
+
+- **Pygame:** It is a set of Python modules designed for writing video games.
+```bash
+pip install pygame
+```
+
+## Controls
+- Click on boxes to mark start(Yellow Coloured) and end point(Sky Blue Coloured).
+- Then make some obstacles(Black Coloured).
+- Then finally press "SPACE" to find the shortest path between the start and end point.
+- The shortest path is represented by "Purple
+
+## Screenshots
+
+<p align="center">
+    <img src="https://github.com/SpecTEviL/Amazing-Python-Scripts/blob/Shortest-Path-finder-GSSoC'21/Shortest-Path-Finder%20(GUI)/1.%20Marked%20Start%20and%20End%20Point.png" alt="1. Marked Start and End Point.png"/>
+    <br>
+    1. Marked Start and End Point
+</p>
+<p align="center">
+    <img src="https://github.com/SpecTEviL/Amazing-Python-Scripts/blob/Shortest-Path-finder-GSSoC'21/Shortest-Path-Finder%20(GUI)/2.%20Made%20Obstacles.png" alt="2. Made Obstacles.png"/>
+    <br>
+    2. Made the Obstacles
+</p>
+<p align="center">
+    <img src="https://github.com/SpecTEviL/Amazing-Python-Scripts/blob/Shortest-Path-finder-GSSoC'21/Shortest-Path-Finder%20(GUI)/3.%20Shortest%20Path%20marked%20in%20Purple%20by%20the%20Algorithm.png" alt="3. Shortest Path marked in Purple by the Algorithm.png"/>
+    <br>
+    3. Shortest Path marked in Purple by the Algorithm
+</p>
+
+## Author
+
+[Vishal Patil](https://github.com/SpecTEviL)

Shortest-Path-Finder (GUI)/2. Made Obstacles.png

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+# Click on boxes to mark start and end point. Then make some obstacles and once done
+# press SPACE to find the shortest path between the start and end point
+
+import pygame as pg
+import math
+from queue import PriorityQueue
+
+
+WIDTH = 595
+WIN = pg.display.set_mode((WIDTH, WIDTH))
+pg.display.set_caption("Shortest Path Finder")
+
+RED = (255, 0, 0)
+GREEN = (0, 255, 0)
+BLUE = (0, 0, 255)
+YELLOW = (255, 255, 0)
+WHITE = (255, 255, 255)
+BLACK = (0, 0, 0)
+GREY = (128, 128, 128)
+TURQUOISE = (64, 244, 208)
+ORANGE = (255, 165, 0)
+PURPLE = (128, 0, 128)
+
+
+class Spot:
+    def __init__(self, row, col, width, total_rows):
+        self.row = row
+        self.col = col
+        self.x = row * width
+        self.y = col * width
+        self.color = WHITE
+        self.neighbour = []
+        self.width = width 
+        self.total_rows = total_rows
+
+    def get_pos(self):
+        return self.row, self.col
+
+    def is_closed(self):
+        return self.color == RED
+
+    def is_open(self):
+        return self.color == GREEN
+
+    def is_barrier(self):
+        return self.color == BLACK
+
+    def is_start(self):
+        return self.color == ORANGE
+
+    def is_end(self):
+        return self.color == TURQUOISE
+
+    def reset(self):
+        self.color = WHITE
+
+    def make_closed(self):
+        self.color = RED
+
+    def make_open(self):
+        self.color = GREEN
+
+    def make_barrier(self):
+        self.color = BLACK
+
+    def make_start(self):
+        self.color = ORANGE
+
+    def make_end(self):
+        self.color = TURQUOISE
+
+    def make_path(self):
+        self.color = PURPLE
+
+    def draw(self, win):
+        pg.draw.rect(win, self.color, (self.x, self.y, self.width, self.width))
+
+    def update_neighbour(self, grid):
+        self.neighbours = []
+        if self.row < self.total_rows - 1 and not grid[self.row + 1][self.col].is_barrier():        # down
+            self.neighbours.append(grid[self.row + 1][self.col])
+
+        if self.row > 0 and not grid[self.row - 1][self.col].is_barrier():                          # up
+            self.neighbours.append(grid[self.row - 1][self.col])
+        
+        if self.col < self.total_rows - 1 and not grid[self.row][self.col + 1].is_barrier():        # right
+            self.neighbours.append(grid[self.row][self.col + 1])
+
+        if self.col > 0 and not grid[self.row][self.col - 1].is_barrier():                          # left
+            self.neighbours.append(grid[self.row][self.col - 1])
+
+
+
+    def __lt__(self, other):
+        return False
+
+    
+def h(p1, p2):
+    x1, y1 = p1
+    x2, y2 = p2
+    return abs(x1 - x2) + abs(y1 - y2)
+    
+
+def reconstruct_path(came_from, current, draw):
+    while current in came_from:
+        current = came_from[current]
+        current.make_path()
+        draw()
+
+
+def algorithm(draw, grid, start, end):
+    count = 0
+    open_set = PriorityQueue()
+    open_set.put((0, count, start))
+    came_from = {}
+    g_score = {spot: float("inf") for row in grid for spot in row}
+    g_score[start] = 0
+    f_score = {spot: float("inf") for row in grid for spot in row}
+    f_score[start] = h(start.get_pos(), end.get_pos())
+    
+    open_set_hash = {start}
+
+    while not open_set.empty():
+        for event in pg.event.get():
+            if event.type == pg.QUIT:
+                pg.quit()
+
+        current = open_set.get()[2]
+        open_set_hash.remove(current)
+
+        if current == end:
+            reconstruct_path(came_from, end, draw)
+            end.make_end()
+            return True
+
+        for neighbour in current.neighbours:
+            temp_g_score = g_score[current] + 1
+
+            if temp_g_score < g_score[neighbour]:
+                came_from[neighbour] = current
+                g_score[neighbour] = temp_g_score
+                f_score[neighbour] = temp_g_score + h(neighbour.get_pos(), end.get_pos())
+                if neighbour not in open_set_hash:
+                    count += 1
+                    open_set.put((f_score[neighbour], count, neighbour))
+                    open_set_hash.add(neighbour)
+                    neighbour.make_open()
+        draw()
+
+        if current != start:
+            current.make_closed()
+
+    return False
+
+
+def make_grid(rows, width):
+    grid = []
+    gap = width // rows
+    for i in range(rows):
+        grid.append([])
+        for j in range(rows):
+            spot = Spot(i, j, gap, rows)
+            grid[i].append(spot)
+
+    return grid
+
+
+def draw_grid(win, rows, width):
+    gap = width // rows
+    for i in range(rows):
+        pg.draw.line(win, GREY, (0, i*gap), (width, i*gap))
+        for j in range(rows):
+            pg.draw.line(win, GREY, (j*gap, 0), (j*gap, width))
+
+
+def draw(win, grid, rows, width):
+    win.fill(WHITE)
+
+    for row in grid:
+        for spot in row:
+            spot.draw(win)
+
+    draw_grid(win, rows, width)
+    pg.display.update()
+
+
+def get_clicked_pos(pos, rows, width):
+    gap = width // rows
+    y, x = pos
+
+    row = y // gap
+    col = x // gap
+
+    return row, col
+
+
+def main(win, width):
+    ROWS = 35
+    grid = make_grid(ROWS, width)
+
+    start = None
+    end = None
+
+    run = True
+    started = False
+    while run:
+        draw(win, grid, ROWS, width)
+        for event in pg.event.get():
+            if event.type == pg.QUIT:
+                run = False
+
+            if pg.mouse.get_pressed()[0]:       # left mouse button
+                pos = pg.mouse.get_pos()
+                row, col = get_clicked_pos(pos, ROWS, width)
+                spot = grid[row][col]
+                if not start and spot != end:
+                    start = spot 
+                    start.make_start()
+
+                elif not end and spot != start:
+                    end = spot
+                    end.make_end()
+                
+                elif spot != end and spot != start:
+                    spot.make_barrier()
+
+            elif pg.mouse.get_pressed()[2]:     # right mouse button
+                pos = pg.mouse.get_pos()
+                row, col = get_clicked_pos(pos, ROWS, width)
+                spot = grid[row][col]
+                spot.reset()
+                if spot == start:
+                    start = None
+                elif spot == end:
+                    end = None
+
+            if event.type == pg.KEYDOWN:
+                if event.key == pg.K_SPACE and start and end:
+                    for row in grid:
+                        for spot in row:
+                            spot.update_neighbour(grid)
+
+                    algorithm(lambda: draw(win, grid, ROWS, width), grid, start, end)
+
+                if event.key == pg.K_c:
+                    start = None
+                    end = None
+                    grid = make_grid(ROWS, width)
+
+    pg.quit()
+
+main(WIN, WIDTH)