Create dota2-senate.py

Author: kamyu104

Python/dota2-senate.py

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+# Time:  O(n)
+# Space: O(n)
+
+# In the world of Dota2, there are two parties: the Radiant and the Dire.
+#
+# The Dota2 senate consists of senators coming from two parties.
+# Now the senate wants to make a decision about a change in the Dota2 game.
+# The voting for this change is a round-based procedure.
+# In each round, each senator can exercise one of the two rights:
+#
+# Ban one senator's right: 
+# A senator can make another senator lose all his rights in this and all the following rounds.
+# Announce the victory: 
+# If this senator found the senators who still have rights to vote are all from the same party,
+# he can announce the victory and make the decision about the change in the game.
+#
+# Given a string representing each senator's party belonging.
+# The character 'R' and 'D' represent the Radiant party and the Dire party respectively.
+# Then if there are n senators, the size of the given string will be n.
+#
+# The round-based procedure starts from the first senator to the last senator in the given order.
+# This procedure will last until the end of voting. All the senators
+# who have lost their rights will be skipped during the procedure.
+#
+# Suppose every senator is smart enough and will play the best strategy for his own party,
+# you need to predict which party will finally announce the victory and make the change in the Dota2 game.
+# The output should be Radiant or Dire.
+#
+# Example 1:
+# Input: "RD"
+# Output: "Radiant"
+# Explanation: The first senator comes from Radiant and he can just ban the next senator's right in the round 1. 
+# And the second senator can't exercise any rights any more since his right has been banned. 
+# And in the round 2, the first senator can just announce the victory since he is the only guy in the senate who can vote.
+# Example 2:
+# Input: "RDD"
+# Output: "Dire"
+# Explanation: 
+# The first senator comes from Radiant and he can just ban the next senator's right in the round 1. 
+# And the second senator can't exercise any rights anymore since his right has been banned. 
+# And the third senator comes from Dire and he can ban the first senator's right in the round 1. 
+# And in the round 2, the third senator can just announce the victory since he is the only guy in the senate who can vote.
+# Note:
+# The length of the given string will in the range [1, 10,000].
+
+class Solution(object):
+    def predictPartyVictory(self, senate):
+        """
+        :type senate: str
+        :rtype: str
+        """
+        n = len(senate)
+        radiant, dire = collections.deque(), collections.deque()
+        for i, c in enumerate(senate):
+            if c == 'R':
+                radiant.append(i)
+            else:
+                dire.append(i)
+        while radiant and dire:
+            r_idx, d_idx = radiant.popleft(), dire.popleft()
+            if r_idx < d_idx:
+                radiant.append(r_idx+n)
+            else:
+                dire.append(d_idx+n)
+        return "Radiant" if len(radiant) > len(dire) else "Dire"