From cc8edccb7ba1f156a72204f8e19a0bed1948a85e Mon Sep 17 00:00:00 2001
From: Sanan507 <227714367+Sanan507@users.noreply.github.com>
Date: Fri, 11 Sep 2026 15:47:29 +0000
Subject: [PATCH] Fix integer overflow in binary search midpoint calculations

---
 .../visualizer/algorithms/sorting/MergeSortModel.java         | 2 +-
 frontend/src/data/algorithmCodeSnippets.ts                    | 2 +-
 frontend/src/data/gymChallenges.ts                            | 2 +-
 frontend/src/workers/simulationWorker.ts                      | 4 ++--
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/backend/src/main/java/com/algorithmrace/visualizer/algorithms/sorting/MergeSortModel.java b/backend/src/main/java/com/algorithmrace/visualizer/algorithms/sorting/MergeSortModel.java
index 5e236a7..62a0ae5 100644
--- a/backend/src/main/java/com/algorithmrace/visualizer/algorithms/sorting/MergeSortModel.java
+++ b/backend/src/main/java/com/algorithmrace/visualizer/algorithms/sorting/MergeSortModel.java
@@ -15,7 +15,7 @@ public MergeSortModel() {
 
   private void buildOps(int l, int r) {
     if (l >= r) return;
-    int m = (l + r) / 2;
+    int m = l + (r - l) / 2;
     buildOps(l, m);
     buildOps(m + 1, r);
     ops.add(new int[] {l, m, r});
diff --git a/frontend/src/data/algorithmCodeSnippets.ts b/frontend/src/data/algorithmCodeSnippets.ts
index c565ced..2062949 100644
--- a/frontend/src/data/algorithmCodeSnippets.ts
+++ b/frontend/src/data/algorithmCodeSnippets.ts
@@ -612,7 +612,7 @@ function merge(L: number[], R: number[]): number[] {
         code: `function binarySearch(arr: number[], target: number): number {
   let lo = 0, hi = arr.length - 1;
   while (lo <= hi) {                          // loop
-    const mid = Math.floor((lo + hi) / 2);
+    const mid = lo + Math.floor((hi - lo) / 2);
     if (arr[mid] === target) return mid;       // found!
     if (arr[mid] < target) lo = mid + 1;      // narrow right
     else hi = mid - 1;                        // narrow left
diff --git a/frontend/src/data/gymChallenges.ts b/frontend/src/data/gymChallenges.ts
index 41598cf..174ec35 100644
--- a/frontend/src/data/gymChallenges.ts
+++ b/frontend/src/data/gymChallenges.ts
@@ -286,7 +286,7 @@ export const BUG_HUNT_CHALLENGES: BugHuntChallenge[] = [
 
   while (low <= high) {
     // ⚠️ Bug line below:
-    const mid = Math.floor((low + high) / 2);
+    const mid = low + Math.floor((high - low) / 2);
 
     if (arr[mid] === target) {
       return mid;
diff --git a/frontend/src/workers/simulationWorker.ts b/frontend/src/workers/simulationWorker.ts
index d1b104d..e7b2ce8 100644
--- a/frontend/src/workers/simulationWorker.ts
+++ b/frontend/src/workers/simulationWorker.ts
@@ -227,7 +227,7 @@ function simulateSingleSortingAlgorithm(
     // MergeSort
     function mergeSort(l: number, r: number) {
       if (l < r) {
-        const m = Math.floor((l + r) / 2);
+        const m = l + Math.floor((r - l) / 2);
         mergeSort(l, m);
         mergeSort(m + 1, r);
         merge(l, m, r);
@@ -535,7 +535,7 @@ function simulateSingleSearchingAlgorithm(
     let right = arr.length - 1;
 
     while (left <= right) {
-      const mid = Math.floor((left + right) / 2);
+      const mid = left + Math.floor((right - left) / 2);
       comparisons++;
       steps++;