From db574a4e4758c210600f8cef960f82440dc3e98a Mon Sep 17 00:00:00 2001
From: Arya Tabaie <15056835+Tabaie@users.noreply.github.com>
Date: Mon, 16 Dec 2024 12:47:51 -0600
Subject: [PATCH] fix mergeIterator

---
 backend/groth16/bn254/mpcsetup/phase2.go | 2 +-
 backend/groth16/internal/utils.go        | 5 ++++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/backend/groth16/bn254/mpcsetup/phase2.go b/backend/groth16/bn254/mpcsetup/phase2.go
index dbd4260e4f..644a8bac22 100644
--- a/backend/groth16/bn254/mpcsetup/phase2.go
+++ b/backend/groth16/bn254/mpcsetup/phase2.go
@@ -277,7 +277,7 @@ func (p *Phase2) Initialize(r1cs *cs.R1CS, commons *SrsCommons) Phase2Evaluation
 	p.Parameters.G2.Sigma = make([]curve.G2Affine, len(commitments))
 
 	for j := range commitments {
-		evals.G1.CKK[i] = make([]curve.G1Affine, 0, len(commitments[j].PrivateCommitted))
+		evals.G1.CKK[j] = make([]curve.G1Affine, 0, len(commitments[j].PrivateCommitted))
 		p.Parameters.G2.Sigma[j] = g2
 	}
 
diff --git a/backend/groth16/internal/utils.go b/backend/groth16/internal/utils.go
index 67648b2104..be4bcf34fa 100644
--- a/backend/groth16/internal/utils.go
+++ b/backend/groth16/internal/utils.go
@@ -57,6 +57,9 @@ func (i *MergeIterator) findLeast() {
 // Peek returns the next smallest value and the index of the slice it came from
 // If the iterator is empty, Peek returns (math.MaxInt, -1)
 func (i *MergeIterator) Peek() (value, index int) {
+	if i.leastIndex == -1 {
+		return math.MaxInt, -1
+	}
 	return i.slices[i.leastIndex][0], i.leastIndex
 }
 
@@ -64,8 +67,8 @@ func (i *MergeIterator) Peek() (value, index int) {
 // If the iterator is empty, Next returns (math.MaxInt, -1)
 func (i *MergeIterator) Next() (value, index int) {
 	value, index = i.Peek()
-	i.findLeast()
 	i.slices[i.leastIndex] = i.slices[i.leastIndex][1:]
+	i.findLeast()
 	return
 }