From 3e0a3628acb3c7258a1bb43ce9fac419276b64ea Mon Sep 17 00:00:00 2001
From: hitonanode <32937551+hitonanode@users.noreply.github.com>
Date: Sun, 18 Jan 2026 14:24:38 +0900
Subject: [PATCH] fix north_east_lattice_paths.hpp

---
 other_algorithms/north_east_lattice_paths.hpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/other_algorithms/north_east_lattice_paths.hpp b/other_algorithms/north_east_lattice_paths.hpp
index 2a4f329c..a30b5937 100644
--- a/other_algorithms/north_east_lattice_paths.hpp
+++ b/other_algorithms/north_east_lattice_paths.hpp
@@ -171,6 +171,7 @@ NorthEastLatticePathsBothBounded(const std::vector<int> &lb, const std::vector<i
     for (int i = 1; i < n; ++i) {
         assert(lb[i - 1] <= lb[i]);
         assert(ub[i - 1] <= ub[i]);
+        if (ub[i - 1] <= lb[i]) return std::vector<MODINT>(ub.back() - lb.back());
     }
 
     for (int i = 0; i < n; ++i) {