From ecead1406dcb47f53b6f075c66d062eafd3c77f4 Mon Sep 17 00:00:00 2001
From: Laurent Perron <lperron@google.com>
Date: Sat, 27 Apr 2024 08:00:50 +0200
Subject: [PATCH] propagate hints when creating var value encoding

---
 ortools/sat/presolve_context.cc | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/ortools/sat/presolve_context.cc b/ortools/sat/presolve_context.cc
index 7fe0c5a497..e30f159553 100644
--- a/ortools/sat/presolve_context.cc
+++ b/ortools/sat/presolve_context.cc
@@ -1492,6 +1492,18 @@ bool PresolveContext::InsertVarValueEncoding(int literal, int ref,
   }
   literal = GetLiteralRepresentative(literal);
   InsertVarValueEncodingInternal(literal, ref, value, /*add_constraints=*/true);
+
+  if (hint_is_loaded_) {
+    const int bool_var = PositiveRef(literal);
+    const int int_var = PositiveRef(ref);
+    if (!hint_has_value_[bool_var] && hint_has_value_[int_var]) {
+      const int64_t int_value = RefIsPositive(ref) ? value : -value;
+      const int64_t hint_value = hint_[int_var] == int_value ? 1 : 0;
+      hint_has_value_[bool_var] = true;
+      hint_[bool_var] = RefIsPositive(literal) ? hint_value : 1 - hint_value;
+    }
+  }
+  
   return true;
 }