Added 3 medium solutions

varunu28 · varunu28 · commit dd85338cfcbd · 2017-11-03T12:07:37.000-07:00
diff --git a/Medium/Arithmetic Slices.java b/Medium/Arithmetic Slices.java
@@ -0,0 +1,16 @@
+class Solution {
+    public int numberOfArithmeticSlices(int[] A) {
+        
+        int curr = 0, sum = 0;
+        for (int i=2; i<A.length; i++)
+            if (A[i]-A[i-1] == A[i-1]-A[i-2]) {
+                curr += 1;
+                sum += curr;
+            } 
+            else {
+                curr = 0;
+            }
+
+        return sum;
+    }
+}
diff --git a/Medium/Palindromic Substrings.java b/Medium/Palindromic Substrings.java
@@ -0,0 +1,20 @@
+class Solution {
+    public int countSubstrings(String s) {
+        int count = 0;
+        for (int i=0;i<s.length();i++) {
+            for (int j=i;j<s.length();j++) {
+                if(isPalindrome(s.substring(i,j+1))) {
+                    count++;
+                }
+            }
+        }
+        
+        return count;
+    }
+    
+    public boolean isPalindrome(String s) {
+        StringBuilder sb = new StringBuilder("");
+        sb.append(s);
+        return sb.reverse().toString().equals(s);
+    }
+}
diff --git a/Medium/Queue Reconstruction By Height.java b/Medium/Queue Reconstruction By Height.java
@@ -0,0 +1,19 @@
+class Solution {
+    public int[][] reconstructQueue(int[][] people) {
+        
+        Arrays.sort(people,new Comparator<int[]>(){
+           @Override
+           public int compare(int[] o1, int[] o2){
+               return o1[0]!=o2[0]?-o1[0]+o2[0]:o1[1]-o2[1];
+           }
+        });
+        
+        List<int[]> res = new LinkedList<>();
+        for(int[] cur : people){
+            res.add(cur[1],cur);       
+        }
+        
+        return res.toArray(new int[people.length][]);
+        
+    }
+}
