diff --git a/02_Dynamic-Programming/13. House Robber Problems/01. House Robber I.py b/02_Dynamic-Programming/12. DP Using 1D Array/10. House Robber III.py
similarity index 100%
rename from 02_Dynamic-Programming/13. House Robber Problems/01. House Robber I.py
rename to 02_Dynamic-Programming/12. DP Using 1D Array/10. House Robber III.py
diff --git a/02_Dynamic-Programming/12. DP Using 1D Array/10. Delete and Earn.py b/02_Dynamic-Programming/12. DP Using 1D Array/11. Delete and Earn.py
similarity index 100%
rename from 02_Dynamic-Programming/12. DP Using 1D Array/10. Delete and Earn.py
rename to 02_Dynamic-Programming/12. DP Using 1D Array/11. Delete and Earn.py
diff --git a/02_Dynamic-Programming/12. DP Using 1D Array/11. Minimum Cost For Tickets.py b/02_Dynamic-Programming/12. DP Using 1D Array/12. Minimum Cost For Tickets.py
similarity index 100%
rename from 02_Dynamic-Programming/12. DP Using 1D Array/11. Minimum Cost For Tickets.py
rename to 02_Dynamic-Programming/12. DP Using 1D Array/12. Minimum Cost For Tickets.py
diff --git a/02_Dynamic-Programming/12. DP Using 1D Array/13. Stone Game.py b/02_Dynamic-Programming/12. DP Using 1D Array/13. Stone Game.py
new file mode 100644
index 00000000..72a364f3
--- /dev/null
+++ b/02_Dynamic-Programming/12. DP Using 1D Array/13. Stone Game.py	
@@ -0,0 +1,30 @@
+# https://leetcode.com/problems/stone-game/
+# https://youtu.be/uhgdXOlGYqE
+'''
+class Solution:
+    def stoneGame(self, piles: List[int]) -> bool:
+        # as sum(piles) is odd and Alice always choose first so there is always an way
+        that Alice will win
+        return True
+        
+'''
+
+class Solution:
+    def stoneGame(self, piles: List[int]) -> bool:
+        dp = {}
+        
+        def dfs(l, r):
+            if l > r: return 0
+            
+            if (l, r) in dp: return dp[(l, r)]
+            
+            even = True if (r - l) % 2 == 0 else False
+            
+            left = piles[l] if even else 0
+            right = piles[r] if even else 0
+            
+            dp[(l, r)] = max(left + dfs(l+1, r), right + dfs(l, r-1))
+            
+            return dp[(l, r)]
+        
+        return dfs(0, len(piles)-1) > sum(piles) // 2
\ No newline at end of file
diff --git a/02_Dynamic-Programming/12. DP Using 1D Array/14. Stone Game II.py b/02_Dynamic-Programming/12. DP Using 1D Array/14. Stone Game II.py
new file mode 100644
index 00000000..9404216f
--- /dev/null
+++ b/02_Dynamic-Programming/12. DP Using 1D Array/14. Stone Game II.py	
@@ -0,0 +1,2 @@
+# https://leetcode.com/problems/stone-game-ii/
+
diff --git a/02_Dynamic-Programming/13. House Robber Problems/02. House Robber II.py b/02_Dynamic-Programming/13. House Robber Problems/02. House Robber II.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/02_Dynamic-Programming/13. House Robber Problems/03. House Robber III.py b/02_Dynamic-Programming/13. House Robber Problems/03. House Robber III.py
deleted file mode 100644
index b28b04f6..00000000
--- a/02_Dynamic-Programming/13. House Robber Problems/03. House Robber III.py	
+++ /dev/null
@@ -1,3 +0,0 @@
-
-
-
diff --git a/11_Binary-Search/05. Find Peak Element.py b/11_Binary-Search/05. Find Peak Element.py
new file mode 100644
index 00000000..baba0081
--- /dev/null
+++ b/11_Binary-Search/05. Find Peak Element.py	
@@ -0,0 +1,38 @@
+# https://leetcode.com/problems/find-peak-element/
+# https://youtu.be/OINnBJTRrMU
+
+class Solution:
+    def findPeakElement(self, nums: List[int]) -> int:
+        n = len(nums)
+        if n == 1: return 0
+        
+        low = 0; high = n-1
+        
+        while low <= high:
+            
+            mid = low + (high - low) // 2
+            # Instead of writting mid = (low + high)//2 we should write mid = low + (high - low)//2 because of INTEGER OVERFLOW in the former case
+            
+            if 0 < mid < n-1:
+                if nums[mid-1] < nums[mid] > nums[mid+1]:
+                    return mid
+                elif nums[mid-1] > nums[mid]:
+                    high = mid - 1
+                else:
+                    low = mid + 1
+                    
+            else:
+                if mid == 0:
+                    if nums[0] > nums[1]:
+                        return 0
+                    else:
+                        return 1
+                if mid == n-1:
+                    if nums[n-1] > nums[n-2]:
+                        return n-1
+                    else:
+                        return n-2
+                    
+# Time: O(n)
+# Space: O(1)
+        
\ No newline at end of file