Graph-3

DistributeWaterInVillage.py

@@ -0,0 +1,28 @@
+from typing import List
+class Solution:
+    def minCostToSupplyWater(self, n: int, wells: List[int], pipes: List[List[int]]) -> int:
+        edges = []
+        parent = [i for i in range(n+1)]
+        for pipe in pipes:
+            edges.append(pipe)
+
+        for i in range(n+1):
+            edges.append([0,i,wells[i-1]])
+        result =0
+        def findparent(x):
+            if parent[x]!=x:
+                parent[x] = findparent(parent[x])
+            return parent[x]
+        edges.sort(key=lambda x:x[2])
+        for edge in edges:
+            x,y = edge[0],edge[1]
+            px = findparent(x)
+            py = findparent(y)
+            if px!=py:
+                result+=edge[2]
+                parent[py] = px
+        return result
+
+
+
+

FindCelebrity.py

@@ -0,0 +1,47 @@
+# The knows API is already defined for you.
+# return a bool, whether a knows b
+def knows(a: int, b: int) -> bool:
+
+# class Solution:
+#     def findCelebrity(self, n: int) -> int:
+#         indegree = [0]*n
+#         for i in range(n):
+#             for j in range(i+1,n):
+#                 if knows(i,j):
+#                     indegree[j]+=1
+#                     indegree[i]-=1
+#                 if knows(j,i):
+#                     indegree[i]+=1
+#                     indegree[j]-=1
+#         for i in range(n):
+#             if indegree[i] == n-1:
+#                 return i
+#         return -1
+
+# class Solution:
+#     def findCelebrity(self, n: int) -> int:
+#         ptncan = 0
+#         for i in range(1,n):
+#             if knows(ptncan,i):
+#                 ptncan = i
+#         for i in range(n):
+#             if i == ptncan : continue
+#             if knows(ptncan,i) or not knows(i,ptncan): return -1
+#         return ptncan
+
+
+class Solution:
+    def findCelebrity(self, n: int) -> int:
+        ptncan = 0
+        for i in range(1,n):
+            if knows(ptncan,i):
+                ptncan = i
+        for i in range(n):
+            if i == ptncan : continue
+            if i<ptncan:
+                if not knows(i,ptncan) or knows(ptncan,i): return -1
+            else:
+                if not knows(i,ptncan): return -1
+        return ptncan
+
+