Initial Commit

Author: SamratChakrabortyy

README.md

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+# AlgoProblems_java
+
+
+This Repository contains java codes for the common algo problems from major coding practice sites.Such as:
+
+  - LeetCode
+
+### LeetCode [/src/com/leetcode]
+
+* [Two-Sum] - [/src/com/leetCode/TwoSum.java]
+* [Best-time-to-buy-and-sell-stock] - [/src/com/leetCode/BuySellStocks.java]
+  
+
+### Todos
+
+ - Improve Time Complexity/ Space complexity or overall complexity
+ - Raise a PR
+
+
+
+
+**Let's code it out!!**
+
+[//]: # (These are reference links used in the body of this note and get stripped out when the markdown processor does its job. There is no need to format nicely because it shouldn't be seen. Thanks SO - http://stackoverflow.com/questions/4823468/store-comments-in-markdown-syntax)
+
+
+  [Two-Sum]: <https://leetcode.com/problems/two-sum/r>
+   [/src/com/leetCode/TwoSum.java]: <https://github.com/LeetCode-ScalerTeam/AlgoProblems_java/blob/master/src/com/leetCode/TwoSum.java>
+   [Best-time-to-buy-and-sell-stock]: <https://leetcode.com/problems/best-time-to-buy-and-sell-stock/>
+   [/src/com/leetCode/BuySellStocks.java]: <https://github.com/LeetCode-ScalerTeam/AlgoProblems_java/blob/master/src/com/leetCode/BuySellStocks.java>
+   
+   

src/com/leetCode/BuySellStocks.java

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+package com.leetCode;
+class BuySellStocksSolution {
+    public int maxProfit(int[] prices) {
+        if(prices.length <= 0)
+                return 0;
+        int max = prices[prices.length -1] , diffMax =0;
+        //System.out.println("max "+max +" diffMax "+diffMax);
+        for(int i = prices.length-2 ; i >= 0 ; i--){
+            if(prices[i] <= max && diffMax < (max - prices[i]))
+                diffMax = max - prices[i];
+            else if(prices[i] > max)
+                max = prices[i];
+            //System.out.println("max "+max +" prices[i]=> "+prices[i]+" diffMax "+diffMax);
+        }
+        return diffMax;
+    }
+}

src/com/leetCode/TwoSum.java

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+package com.leetCode;
+
+import java.util.*;
+
+class TwoSumsSolution {
+    public int[] twoSum(int[] nums, int target) {
+        Map<Integer, Integer> seenMap = new HashMap<>();
+        int res[] = new int[2];
+        for(int i = 0 ; i < nums.length ; i++){
+            int temp = target - nums[i];
+            //System.out.println("temp -> "+temp+" seenMap.containsKey(temp) ->  "+seenMap.containsKey(temp));
+            if(seenMap.containsKey(temp)){
+                //System.out.println("In If");
+                res[0] = seenMap.get(temp);
+                res[1] = i;
+                return res;
+            }
+            else{
+                //System.out.println("else ");
+                seenMap.put(nums[i],i);
+            }
+            //System.out.println(seenMap);
+        }
+        return res;
+    }
+}