add 649

Author: fishercoder1534

README.md

@@ -23,6 +23,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |652|[Find Duplicate Subtrees](https://leetcode.com/problems/find-duplicate-subtrees/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_652.java) | O(n) |O(n) | Medium | Tree
 |651|[4 Keys Keyboard](https://leetcode.com/problems/4-keys-keyboard/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_651.java) | O(n^2) |O(n) | Medium | DP
 |650|[2 Keys Keyboard](https://leetcode.com/problems/2-keys-keyboard/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_650.java) | O(n^2) |O(n) | Medium | DP
+|649|[Dota2 Senate](https://leetcode.com/problems/dota2-senate/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_649.java) | O(n) |O(n) | Medium | Greedy
 |648|[Replace Words](https://leetcode.com/problems/replace-words/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_648.java) | O(n) |O(n) | Medium | Trie
 |647|[Palindromic Substrings](https://leetcode.com/problems/palindromic-substrings/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_647.java) | O(n^2) |O(1) | Medium | DP
 |646|[Maximum Length of Pair Chain](https://leetcode.com/problems/maximum-length-of-pair-chain/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_646.java) | O(nlogn) |O(1) | Medium | DP

src/main/java/com/fishercoder/solutions/_649.java

@@ -0,0 +1,74 @@
+package com.fishercoder.solutions;
+
+import java.util.LinkedList;
+import java.util.Queue;
+
+/**
+ * 649. Dota2 Senate
+ *
+ * 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:
+
+ 1. Ban one senator's right:
+ A senator can make another senator lose all his rights in this and all the following rounds.
+ 2. 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].
+
+ */
+public class _649 {
+
+    public String predictPartyVictory(String senate) {
+        Queue<Integer> radiantQ = new LinkedList<>();
+        Queue<Integer> direQ = new LinkedList<>();
+        int len = senate.length();
+        for (int i = 0; i < len; i++) {
+            if (senate.charAt(i) == 'R') radiantQ.offer(i);
+            else direQ.offer(i);
+        }
+        while (!radiantQ.isEmpty() && !direQ.isEmpty()) {
+            int radiantIndex = radiantQ.poll();
+            int direIndex = direQ.poll();
+            if (radiantIndex < direIndex) {
+                /**Radiant will ban Dire in this case, so we'll add radiant index back to the queue plus n*/
+                radiantQ.offer(radiantIndex + len);
+            } else {
+                direQ.offer(direIndex + len);
+            }
+        }
+        return radiantQ.isEmpty() ? "Dire" : "Radiant";
+    }
+}

src/test/java/com/fishercoder/_649Test.java

@@ -0,0 +1,54 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._649;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Created by fishercoder on 5/8/17.
+ */
+public class _649Test {
+    private static _649 test;
+
+    @BeforeClass
+    public static void setup(){
+        test = new _649();
+    }
+
+    @Test
+    public void test1(){
+        assertEquals("Dire", test.predictPartyVictory("RDDDR"));
+    }
+
+    @Test
+    public void test2(){
+        assertEquals("Radiant", test.predictPartyVictory("RD"));
+    }
+
+    @Test
+    public void test3(){
+        assertEquals("Dire", test.predictPartyVictory("RDD"));
+    }
+
+    @Test
+    public void test4(){
+        assertEquals("Radiant", test.predictPartyVictory("RDDR"));
+    }
+
+    @Test
+    public void test5(){
+        assertEquals("Dire", test.predictPartyVictory("RDDRD"));
+    }
+
+    @Test
+    public void test6(){
+        assertEquals("Dire", test.predictPartyVictory("RDDDDDRR"));
+    }
+
+    @Test
+    public void test7(){
+        assertEquals("Dire", test.predictPartyVictory("RDDDDRR"));
+    }
+}