From 939032e7268e25c3b18ac8f2de2e3e6046a7aa6e Mon Sep 17 00:00:00 2001
From: Shubham Nag <43213463+shubhamnag14@users.noreply.github.com>
Date: Thu, 21 Oct 2021 01:26:14 +0530
Subject: [PATCH] Astar algorithm

A* is a graph traversal and path search algorithm, which is often used in many fields of computer science due to its completeness, optimality, and optimal efficiency.
#shubhamnag14
---
 SORTING/py/A-star Algorithm.py | 82 ++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 SORTING/py/A-star Algorithm.py

diff --git a/SORTING/py/A-star Algorithm.py b/SORTING/py/A-star Algorithm.py
new file mode 100644
index 0000000..4faf9d6
--- /dev/null
+++ b/SORTING/py/A-star Algorithm.py	
@@ -0,0 +1,82 @@
+from queue import *
+class State(object):
+    def __init__(self,value, parent, start=0,goal=0,solver=0):
+        self.children = []
+        self.parent = parent
+        self.value = value
+        self.dist = 0
+        if parent:
+            self.path = parent.path[:]
+            self.path.append(value)
+            self.start = parent.start
+            self.goal = parent.goal
+            self.solver = parent.solver
+        else:
+            self.path = [value]
+            self.start = start
+            self.goal = goal
+            self.solver = solver
+
+    def GetDist(self):
+        pass
+    def CreateChildren(self):
+        pass
+
+
+class State_String(State):
+    def __init__(self, value, parent, start=0, goal=0, solver=0):
+        super(State_String,self).__init__(value, parent, start, goal, solver)
+        self.dist =self.GetDist()
+    def GetDist(self):
+        if self.value == self.goal:
+            return 0
+        dist = 0
+        for i in range(len(self.goal)):
+            letter = self.goal[i]
+            dist += abs(i - self.value.index(letter))
+        return dist
+    def CreateChildren(self):
+        if not self.children:
+            for i in range(len(self.goal)-1):
+                val = self.value
+                val = val[:i]+val[i+1]+val[i]+val[i+2]
+                child = State_String(val,self)
+                self.children.append(child)
+
+class Astar_Solver:
+    def __init__(self,start,goal):
+        self.path = []
+        self.visitedQueue = []
+        self.priorityQueue = PriorityQueue()
+        self.start = start
+        self.goal = goal
+
+    def Solver(self):
+        startState = State_String(self.start,0,self.start,self.goal,self)
+        count = 0
+        self.priorityQueue.put((0,count,startState))
+        while(not self.path and self.priorityQueue.qsize()):
+            closestChild = self.priorityQueue.get()[2]
+            closestChild.CreateChildren()
+            self.visitedQueue.append(closestChild.value)
+            for child in closestChild:
+                if child.value not in  self.visitedQueue:
+                    count += 1
+
+                    if not child.dist:
+                        self.path = child.path
+                        break
+                    self.priorityQueue.put((child.dist,count,child))
+
+        if not self.path:
+            print("Goal"+self.goal+"is not possible")
+        return self.path
+
+        if __name__ == "__main__":
+            start1 = "cdabfe"
+            goal1 = "abcdef"
+            print("Starting")
+            a = Astar_Solver(start1,goal1)
+            a.Solve()
+            for i in xrange(len(a.path)):
+                print("%d" %i + a.path[i])
\ No newline at end of file