Accepted

Author: gouthampradhan

problems/src/CoinChange2.java

@@ -0,0 +1,37 @@
+import java.util.Arrays;
+
+/**
+ * Created by gouthamvidyapradhan on 22/03/2017.
+ */
+public class CoinChange2
+{
+    /**
+     * Main method
+     * @param args
+     * @throws Exception
+     */
+    public static void main(String[] args) throws Exception
+    {
+        int[] coins = {1,2,5};
+        System.out.println(new CoinChange2().change(5, coins));
+    }
+
+    public int change(int amount, int[] coins)
+    {
+        int[][] dp = new int[coins.length][amount + 1];
+        for(int i = 0, l = coins.length; i < l; i ++)
+            Arrays.fill(dp[i], -1);
+        return dp(dp, 0, coins, coins.length, amount);
+    }
+
+    private int dp(int[][] dp, int i, int[] coins, int l, int n)
+    {
+        if(n == 0) return 1;
+        else if(i >= l) return 0;
+        if(n < 0) return 0;
+        if(dp[i][n] != -1) return dp[i][n];
+        dp[i][n] = dp(dp, i + 1, coins, l, n) + dp(dp, i, coins, l, n - coins[i]);
+        return dp[i][n];
+    }
+
+}

problems/src/RandomizedSet.java

@@ -0,0 +1,86 @@
+import java.util.*;
+
+/**
+ * Created by gouthamvidyapradhan on 23/03/2017.
+ * Accepted
+ */
+public class RandomizedSet
+{
+    private Map<Integer, Integer> map;
+    private List<Integer> list;
+    private Random random;
+    /** Initialize your data structure here. */
+    public RandomizedSet()
+    {
+        map = new HashMap<>();
+        list = new ArrayList<>();
+        random = new Random();
+    }
+
+    /**
+     * Main method
+     * @param args
+     * @throws Exception
+     */
+    public static void main(String[] args) throws Exception
+    {
+        RandomizedSet rSet = new RandomizedSet();
+        System.out.println(rSet.getRandom());
+        System.out.println(rSet.insert(1));
+        System.out.println(rSet.insert(2));
+        System.out.println(rSet.insert(2));
+        System.out.println(rSet.insert(3));
+        System.out.println(rSet.remove(2));
+        System.out.println(rSet.insert(2));
+        System.out.println(rSet.getRandom());
+        System.out.println(rSet.insert(234));
+        System.out.println(rSet.insert(23));
+        System.out.println(rSet.insert(22));
+        System.out.println(rSet.getRandom());
+        System.out.println(rSet.remove(245));
+        System.out.println(rSet.remove(234));
+        System.out.println(rSet.getRandom());
+    }
+
+    /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
+    public boolean insert(int val)
+    {
+        if(!map.keySet().contains(val))
+        {
+            int pos = list.size();
+            map.put(val, pos);
+            list.add(val);
+            return true;
+        }
+        return false;
+    }
+
+    /** Removes a value from the set. Returns true if the set contained the specified element. */
+    public boolean remove(int val)
+    {
+        if(map.containsKey(val))
+        {
+            int size = list.size();
+            int posVal = map.get(val);
+            if(posVal < (size - 1))
+            {
+                int last = list.get(size - 1);
+                map.put(last, posVal);
+                list.set(posVal, last);
+            }
+            map.remove(val);
+            list.remove(size - 1);
+            return true;
+        }
+        return false;
+    }
+
+    /** Get a random element from the set. */
+    public int getRandom()
+    {
+        /*if(list.size() == 0) return 0;
+        else if (list.size() == 1) return list.get(0);*/
+        return list.get(random.nextInt(list.size() - 1));
+    }
+
+}