add dfs

Author: ss892714028

gifs/astar.gif

@@ -1 +1,85 @@
-def a_star():
+import sys
+import numpy as np
+from config import config
+from collections import deque
+import time
+import pygame
+from queue import PriorityQueue
+import copy
+
+
+def is_valid(mat, row, col):
+    M, N = mat.shape
+    return (row >= 0) and (row < M) and (col >= 0) and (col < N) \
+        and mat[row][col] == 0
+
+
+def manhattan_distance(x1, y1, x2, y2):
+    return abs(x1 - x2) + abs(y1 - y2)
+
+
+def a_star(win, startEnd, walls):
+    start, end = startEnd
+    mat = np.zeros([config['board']['w'], config['board']['h']])
+    for i in walls:
+        mat[i] = 1
+
+    # explore 4 neighbors
+    row = [-1, 0, 0, 1]
+    col = [0, -1, 1, 0]
+
+    q = PriorityQueue()
+    count = 0
+    q.put((0, count, start))
+    g_score = {}
+    for i in range(mat.shape[0]):
+        for j in range(mat.shape[1]):
+            g_score[(i, j)] = float('inf')
+
+    f_score = copy.deepcopy(g_score)
+    g_score[start] = 0
+    f_score[start] = manhattan_distance(*start, *end)
+    q_hash = {start}
+    came_from = {}
+    while not q.empty():
+        for event in pygame.event.get():
+            if event.type == pygame.QUIT:
+                pygame.quit()
+        current = q.get()[2]
+        q_hash.remove(current)
+
+        for k in range(4):
+            coordinate = (current[0] + row[k], current[1] + col[k])
+
+            if is_valid(mat, *coordinate):
+                temp_g_score = g_score[current] + 1
+                if temp_g_score < g_score[coordinate]:
+                    came_from[coordinate] = current
+                    g_score[coordinate] = temp_g_score
+                    f_score[coordinate] = temp_g_score + manhattan_distance(*coordinate, *end)
+                    if coordinate not in q_hash:
+                        count += 1
+                        q_hash.add(coordinate)
+                        q.put((f_score[coordinate], count, coordinate))
+                        win.write('*', *coordinate, fgcolor='green')
+                        pygame.time.wait(5)
+        if current == end:
+            count = 0
+            win.write('@', *end)
+            while current in came_from:
+                for event in pygame.event.get():
+                    if event.type == pygame.QUIT:
+                        pygame.quit()
+                current = came_from[current]
+                win.write('+', *current, fgcolor='red')
+                count += 1
+                pygame.time.wait(20)
+            win.write('@', *start)
+            win.write(f"The shortest path from source to destination has length {count}", 1, 1)
+            break
+    win.write("Destination can't be reached from a given source", 1, 1)
+
+
+
+
+

gifs/dfs.gif renamed to gifs/dfs-nonoptimal.gif

@@ -3,6 +3,7 @@
 from config import config
 from collections import deque
 import time
+import pygame
 
 
 def is_valid(mat, visited, row, col):
@@ -33,6 +34,10 @@ def bfs(win, startEnd, walls):
     min_dist = sys.maxsize
 
     while q:
+        for event in pygame.event.get():
+            # Quit if the user closes the window.
+            if event.type == pygame.QUIT:
+                return
         (start_x, start_y, dist, add) = q.popleft()
         if start_x == end_x and start_y == end_y:
             min_dist = dist
@@ -50,10 +55,15 @@ def bfs(win, startEnd, walls):
         # find path
         start_x, start_y = startEnd[0]
         for i in range(len(add)):
+            for event in pygame.event.get():
+                # Quit if the user closes the window.
+                if event.type == pygame.QUIT:
+                    return
             index = move.index(add[i])
             start_x, start_y = start_x + row[index], start_y + col[index]
             win.write('+', start_x, start_y, fgcolor='red')
             time.sleep(0.02)
+
         win.write('@', end_x, end_y)
         win.write(f"The shortest path from source to destination has length {min_dist}", 1, 1)
     else:

src/a_star.py

@@ -3,5 +3,5 @@
         'w': 50,
         'h': 50
     },
-    "algo": 'dfs'
+    "algo": 'astar'
 }

src/bfs.py

@@ -8,6 +8,7 @@
 import time
 from bfs import bfs
 from dfs import dfs
+from a_star import a_star
 
 
 def drawer():
@@ -45,6 +46,9 @@ def drawer():
                     bfs(win, startEnd, walls)
                 if config['algo'] == 'dfs':
                     dfs(win, startEnd, walls)
+                if config['algo'] == 'astar':
+                    a_star(win, startEnd, walls)
+
 
 
 if __name__ == "__main__":