Create Split Array by Prime Indices.java

varunu28 · web-flow · commit f4698d4de877 · 2025-07-19T12:09:26.000-07:00
diff --git a/Medium/Split Array by Prime Indices.java b/Medium/Split Array by Prime Indices.java
@@ -0,0 +1,36 @@
+class Solution {
+    public long splitArray(int[] nums) {
+        Set<Integer> primeIndices = getPrimeIndices(nums.length);
+        long primeSum = 0;
+        long nonPrimeSum = 0;
+        for (int i = 0; i < nums.length; i++) {
+            if (primeIndices.contains(i)) {
+                primeSum += nums[i];
+            } else {
+                nonPrimeSum += nums[i];
+            }
+        }
+        return Math.abs(primeSum - nonPrimeSum);
+    }
+
+    private Set<Integer> getPrimeIndices(int n) {
+        boolean[] isPrime = new boolean[n + 1];
+        for (int i = 2; i <= n; i++) {
+            isPrime[i] = true;
+        }
+        for (int i = 2; i * i <= n; i++) {
+            if (isPrime[i]) {
+                for (int j = i * i; j <= n; j += i) {
+                    isPrime[j] = false;
+                }
+            }
+        }
+        Set<Integer> primeIndices = new HashSet<>();
+        for (int i = 2; i <= n; i++) {
+            if (isPrime[i]) {
+                primeIndices.add(i);
+            }
+        }
+        return primeIndices;
+    }
+}
