Solution to write a Program to calculate prefix even sum of an index in an array

deepcodingios · deepcodingios · commit 7d52ddfbebfb · 2022-08-03T22:42:12.000+05:30
diff --git a/src/Arrays/EquilibriumIndex.java b/src/Arrays/EquilibriumIndex.java
@@ -47,6 +47,8 @@ static int getPrefixSumOfAnIndex(int index, ArrayList<Integer> arrayList){
         return prefixSum;
     }
 
+
+
     static int findEquilibriumIndex(ArrayList<Integer> arrayList) {
 
         ArrayList<Integer> prefixArray = getPrefixSumArrayOfAnArray(arrayList);         
diff --git a/src/Arrays/PrefixSumProblems.java b/src/Arrays/PrefixSumProblems.java
@@ -0,0 +1,39 @@
+package Arrays;
+
+import java.util.ArrayList;
+
+public class PrefixSumProblems {
+    public static void main(String[] args) {
+        ArrayList<Integer> arrayList = new ArrayList<>(100);
+
+        //[3,-2,4,6,-3,5]
+        arrayList.add(2);
+        arrayList.add(4);
+        arrayList.add(3);
+        arrayList.add(1);
+        arrayList.add(5);
+//        arrayList.add(5);
+//        arrayList.add(0);
+        int prefixEvenSum = getPrefixEvenSumOfAnIndex(5,arrayList);
+        System.out.println(prefixEvenSum);
+    }
+
+    static int getPrefixEvenSumOfAnIndex(int index, ArrayList<Integer> arrayList){
+
+        int prefixEvenSum = arrayList.get(0);
+
+        if (arrayList.size() == 1){
+            prefixEvenSum = arrayList.get(0);
+            return prefixEvenSum;
+        }
+
+        for (int i = 1; i < arrayList.size(); i++) {
+
+            if (i % 2 == 0){
+                prefixEvenSum = prefixEvenSum + arrayList.get(i);
+            }
+        }
+
+        return prefixEvenSum;
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -47,6 +47,8 @@ static int getPrefixSumOfAnIndex(int index, ArrayList<Integer> arrayList){`
`47`	`47`	`return prefixSum;`
`48`	`48`	`}`
`49`	`49`
	`50`	`+`
	`51`	`+`
`50`	`52`	`static int findEquilibriumIndex(ArrayList<Integer> arrayList) {`
`51`	`53`
`52`	`54`	`ArrayList<Integer> prefixArray = getPrefixSumArrayOfAnArray(arrayList);`