Leetcode_Problems

src/main/java/com/leetcode/dynamicprogramming/Leetcode_516_Longest_Palindromic_SubSequence.java

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+ public static void display_1D(int[] arr) 
+    {
+        for (int ele : arr) 
+        {
+            System.out.print(ele + "\t");
+        }
+        System.out.println();
+    }
+    public static void display_2D(int[][] arr) 
+    {
+        for (int[] ar : arr) 
+        {
+            display_1D(ar);
+        }
+        System.out.println();
+    }
+
+public static int Leetcode_516_Longest_Pallindromic_SubSequence_Tabulation(String str, int si, int ei, int[][] dp, boolean[][] isPalindrome)
+    {
+        int n=str.length();
+        for(int gap = 0; gap < n; gap++)
+        {
+            for(si = 0; si < n - gap; si++)
+            {
+                ei = si + gap;
+
+                if(isPalindrome[si][ei])
+                {
+                    dp[si][ei] = ei-si+1;
+                    continue;
+                }
+
+                int len=0;
+                if(str.charAt(si) == str.charAt(ei))
+                {
+                    len = dp[si+1][ei-1] + 2;
+                }
+                else
+                {
+                    len = Math.max(dp[si+1][ei], dp[si][ei-1]);
+                }
+
+                dp[si][ei] = len;
+            }
+        }
+
+        return dp[0][str.length()-1];
+    }
+
+    public static void Leetcode_516_Longest_Pallindromic_SubSequence()
+    {
+        String str = "geeksforgeeks";
+        int n = str.length();
+        int si = 0, ei = n - 1;
+        int[][] dp = new int[n][n];
+
+        boolean[][] isPalindrome = is_Pallindrome_SubString(str);
+        System.out.println("Tabulation :- " + Leetcode_516_Longest_Pallindromic_SubSequence_Tabulation(str, si, ei, dp, isPalindrome));
+        display_2D(dp);
+    }

src/main/java/com/leetcode/dynamicprogramming/Leetcode_70_Climb_Stairs.java

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+public static int LeetCode_70_Climbing_Stairs_Memoization(int n, int[] dp) 
+    {
+        if (n <= 1) 
+        {
+            return dp[n] = 1;
+        }
+
+        if (dp[n] != 0) 
+        {
+            return dp[n];
+        }
+
+        int ans = LeetCode_70_Climbing_Stairs_Memoization(n - 1, dp)
+                + LeetCode_70_Climbing_Stairs_Memoization(n - 2, dp);
+
+        return dp[n] = ans;
+    }
+    public static int LeetCode_70_Climbing_Stairs_Tabulation(int n, int[] dp) 
+    {
+        int N = n;
+        for (n = 0; n <= N; n++) 
+        {
+            if (n <= 1) 
+            {
+                dp[n] = 1;
+                continue;
+            }
+
+            int ans = dp[n - 1] + dp[n - 2];
+
+            dp[n] = ans;
+        }
+
+        return dp[N];
+    }
+    public static int LeetCode_70_Climbing_Stairs_Better(int n) 
+    {
+        int a = 1;
+        int b = 1;
+        int sum = 0;
+
+        for (int i = 2; i <= n; i++) 
+        {
+            sum = a + b;
+            a = b;
+            b = sum;
+        }
+
+        return sum;
+    }
+    public static void LeetCode_70_Climbing_Stairs()
+    {
+        int n=7;
+        int[] dp = new int[n+1];
+        System.out.println("Memoization :- " + LeetCode_70_Climbing_Stairs_Memoization(n, dp));
+        display_1D(dp);
+        System.out.println("Tabulation :- " + LeetCode_70_Climbing_Stairs_Tabulation(n, dp));
+        display_1D(dp);
+        System.out.println("Better :- " + LeetCode_70_Climbing_Stairs_Better(n));
+    }