added some spoj problem and problem sums from poi

Author: gauraviuiux

New folder/dijkstra.py

@@ -0,0 +1,75 @@
+from collections import defaultdict
+
+import heapq
+
+# initialisation
+
+n = 5
+
+graph = defaultdict(list)
+
+dist = [float('inf')]*n
+
+heap = []
+
+# adding the following edges
+
+edges = [(0, 1), (1, 2), (2, 4), (4, 3), (3, 0), (3, 1), (1, 4)]
+
+weight = [6, 5, 5, 1, 1, 2, 2];
+
+for i in range (0, len(edges)):
+
+    x = edges[i][0]
+
+    y = edges[i][1]
+
+    w = weight[i];
+
+    #Adding the weighted edges
+
+    graph[x].append((w, y))
+
+    graph[y].append((w, x))
+
+ 
+
+src = 0
+
+# add edge to heap with edge weight priority
+
+heapq.heappush(heap, (0, src))
+
+dist[0] = 0
+
+ 
+
+while len(heap) > 0:
+
+    # heap[0] gives the top element in the min heap
+
+    node = heap[0][1]
+
+    heapq.heappop(heap)
+
+    for i in range(0, len(graph[node])):
+
+        nextnode = graph[node][i][1]
+
+        w = graph[node][i][0]
+
+ 
+
+        if dist[nextnode] > dist[node] + w:
+
+            dist[nextnode] = dist[node] + w;
+
+            heapq.heappush(heap, (dist[nextnode], nextnode))
+
+ 
+
+print("Shortest distance from source vertex " + str(src) + " to vertex")
+
+for i in range(0,n):
+
+    print(str(i) + ": " + str(dist[i]))

codechefcycles.py

@@ -0,0 +1,77 @@
+n = int(input())
+
+perm = [0] + list(map(int, input().split()))
+
+ 
+
+index = 1
+
+last = 1
+
+dim = 0
+
+ 
+
+ans = []
+
+ans.append([])
+
+visited = [True, True] + [False]*(n-1)
+
+ 
+
+def first_unvisited():
+
+    for i in range(n+1):
+
+        if not visited[i]:
+
+            return i
+
+    else:
+
+        return -1
+
+ 
+
+ 
+
+while True:
+
+    ans[dim].append(index)
+
+    index = perm[index]
+
+    visited[index] = True
+
+ 
+
+    if index == last:
+
+        unvisited_ind = first_unvisited()
+
+        ans[dim].append(index)
+
+        
+
+        if unvisited_ind == -1:
+
+            break
+
+        else:
+
+            index = unvisited_ind
+
+            last = index
+
+            ans.append([])
+
+            dim+=1
+
+ 
+
+print(dim+1)
+
+for i in range(dim+1):
+
+    print(" ".join(map(str, ans[i])))

codechefwealthdisparity.py

@@ -0,0 +1,41 @@
+arr=list(map(int,input().split()))
+n=arr[0]
+graph=[[]for i in range(n+1)]
+cost=[]
+for i in range(1,n+1):
+	cost.append(arr[i])
+cost=[0]+cost
+manager=[]
+for i in range(n+1,2*n+1):
+	manager.append(arr[i])
+manager=[0]+manager
+for i in range(1,n+1):
+	k=manager[i]
+	if manager[i]!=-1:
+		graph[k].append(i)
+
+
+idx=manager.index(-1)
+
+max1=0
+zx=idx
+zy=-1
+for i in range(1,n+1):
+	zz=cost[idx]
+	if manager[i]!=-1:
+		zz=zz-cost[i]
+		if zz>max1:
+			zy=i
+			max1=zz
+		
+for i in range(1,n+1):
+	if i!=idx:
+		for k in graph[i]:
+			newcost=cost[i]-cost[k]
+			if newcost>max1:
+				zx=i
+				zy=k
+				max1=newcost
+
+
+print(max1)

codeforcesnewreform.py

@@ -0,0 +1,32 @@
+n,m=map(int,input().split())
+
+graph=[[]for i in range(n)]
+for i in range(m):
+	a,b=map(int,input().split())
+	a=a-1
+	b=b-1
+	graph[a].append(b)
+	graph[b].append(a)
+	
+visited=[0 for i in range(n)]
+tree=True
+def dfs(src,par):
+	visited[src]=1
+
+	for child in graph[src]:
+		if visited[child]==0:
+
+			dfs(child,src)
+		elif child!=par:
+			tree=False
+	return
+
+ans=0
+for src in range(n):
+	if visited[src]==0:
+		if  dfs(src,-1):
+			ans=ans+1
+
+print(ans)
+
+

hackerrankroadsandlibrary.py

@@ -0,0 +1,33 @@
+for _ in range(int(input())):
+    n,m,lib,road=map(int,input().split())
+    graph =[[]for i in range(n)]
+    for i in range(m):
+        a,b=map(int,input().split())
+        a=a-1
+        b=b-1
+        graph[a].append(b)
+        graph[b].append(a)
+    count=[0 for i in range(n)]
+    visited=[0 for i in range(n)]
+    countroad=0
+    def  dfs(src):
+        global countroad
+        visited[src]=1
+        
+        for child in graph[src]:
+            if visited[child]==0:
+                countroad+=1
+                dfs(child)
+    count=0
+    for i in range(n):
+        if visited[i]==0:
+            count+=1
+            dfs(i)
+    chuchi=0
+    if lib<=road:
+        print(n*lib)
+    else:
+        chuchi=lib*count+countroad*road
+        print(chuchi)
+
+

priorityqueue-master/LICENSE.txt

@@ -0,0 +1,7 @@
+Copyright (c) 2015 Matthew Westcott
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

priorityqueue-master/README.txt

@@ -0,0 +1,60 @@
+priorityqueue.py
+
+Priority Queue Implementation with a O(log n) Remove Method
+
+This project implements min- amd max-oriented priority queues based on binary
+heaps. I found the need for a priority queue with a O(log n) remove method.
+This can't be achieved with any of Python's built in collections including
+the heapq module, so I built my own. The heap is arranged according to a given
+key function.
+
+Usage:
+    >>> from priorityqueue import MinHeapPriorityQueue
+    >>> items = [4, 0, 1, 3, 2]
+    >>> pq = MinHeapPriorityQueue(items)
+    >>> pq.pop()
+    0
+
+    A priority queue accepts an optional key function.
+    >>> items = ['yy', 'ttttttt', 'z', 'wwww', 'uuuuuu', 'vvvvv', 'xxx']
+    >>> pq = MinHeapPriorityQueue(items, key=len)
+    >>> pq.pop()
+    'z'
+    >>> pq.pop()
+    'yy'
+
+    Internally, the queue is a list of tokens of type 'Locator', which contain
+    the priority value, the item itself, and its current index in the heap.
+    The index field is updated whenever the heap is modified. This is what
+    allows us to remove in O(log n). Appending an item returns it's Locator.
+    >>> token = pq.append('a')
+    >>> token
+    Locator(value=1, item='a', index=0)
+    >>> pq.remove(token)
+    'a'
+
+    If we want to be able to remove any item in the list we can maintain an
+    auxiliary dictionary mapping items to their Locators. Here's a simple
+    example with unique items:
+    >>> items = [12, 46, 89, 101, 72, 81]
+    >>> pq = MinHeapPriorityQueue()
+    >>> locs = {}
+    >>> for item in items:
+    ...    locs[item] = pq.append(item)
+    >>> locs[46]
+    Locator(value=46, item=46, index=1)
+    >>> pq.remove(locs[46])
+    46
+
+    Iterating with 'for item in pq' or iter() will produce the items, not the
+    Locator instances used in the internal representation. The items will be
+    generated in sorted order.
+    >>> items = [3, 1, 0, 2, 4]
+    >>> pq = MinHeapPriorityQueue(items)
+    >>> for item in pq:
+    ...     print(item)
+    0
+    1
+    2
+    3
+    4