Merge pull request #249 from Sakshamgupta90/master

Burst_Balloon.java

Author: SarthakKeshari

LeetCode/Burst_Balloon.java

@@ -0,0 +1,52 @@
+/   // Leetcode Ques No. : 312
+    // Problem Link: https://leetcode.com/problems/burst-balloons/
+
+
+    ***** problem statement *****
+
+    /*
+     You are given n balloons, indexed from 0 to n - 1. Each balloon is painted with a number on it represented by an array nums. You are asked to burst all the balloons.
+     If you burst the ith balloon, you will get nums[i - 1] * nums[i] * nums[i + 1] coins. If i - 1 or i + 1 goes out of bounds of the array, then treat it as if there is a balloon with a 1 painted on it.
+     Return the maximum coins you can collect by bursting the balloons wisely.
+    */
+
+
+    ***** Solution *****
+
+
+
+     public int maxCoins_memo(int[] nums , int si , int ei , int[][] dp){ //si = starting index , ei = ending index
+         if(dp[si][ei] != 0)
+             return dp[si][ei];
+
+         int lele = si == 0 ? 1 : nums[si - 1]; //lele = leftelement
+         int rele = ei == nums.length - 1 ? 1 : nums[ei + 1]; //rele = rightelement
+
+         int maxCoin = 0;
+         for(int cut = si; cut <= ei; cut++){
+             int lcost = cut == si ? 0 : maxCoins_memo(nums , si , cut - 1 , dp); //lcost:leftcost
+             int rcost = cut == ei ? 0 : maxCoins_memo(nums , cut + 1 , ei , dp); //rcost:rightcost
+
+             maxCoin = Math.max(maxCoin , lcost + lele * nums[cut] * rele + rcost); // maxcoin means the maximum number of coins collect after balloon burst
+         }
+
+         return dp[si][ei] = maxCoin; 
+     }
+     public int maxCoins(int[] nums) {
+         int n = nums.length;
+         int[][] dp = new int[n][n];
+
+         return maxCoins_memo(nums , 0 , n - 1 , dp);
+     }
+
+
+
+
+
+    /*
+     Sample input: [3,1,5,8]
+                   
+     Sample Output: 167
+     
+     
+     */