# UNDF: UNDF-2026-000001003
--- a/src/Battlescape/AIModule.h
+++ b/src/Battlescape/AIModule.h
@@ -20,6 +20,7 @@
 #include <yaml-cpp/yaml.h>
 #include "BattlescapeGame.h"
 #include "Position.h"
+#include <unordered_set>
 #include "../Savegame/BattleUnit.h"
 #include <vector>

@@ -50,7 +51,7 @@
 	bool _traceAI, _didPsi;
 	int _AIMode, _intelligence, _closestDist;
 	Node *_fromNode, *_toNode;
-	std::vector<int> _reachable, _reachableWithAttack, _wasHitBy;
+	std::unordered_set<int> _reachable, _reachableWithAttack;
+	std::vector<int> _wasHitBy;
 	BattleActionType _reserve;
 	UnitFaction _targetFaction;
 public:
--- a/src/Battlescape/AIModule.cpp
+++ b/src/Battlescape/AIModule.cpp
@@ -150,7 +150,10 @@
 	_attackAction->actor = _unit;
 	_attackAction->weapon = action->weapon;
 	_attackAction->number = action->number;
 	_escapeAction->number = action->number;
-	_reachable = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits());
+	{
+		std::vector<int> rv = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits());
+		_reachable = std::unordered_set<int>(rv.begin(), rv.end());
+	}
 	_wasHitBy.clear();

@@ -197,7 +200,8 @@
 				_blaster = true;
-				_reachableWithAttack = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits() - _unit->getActionTUs(BA_AIMEDSHOT, action->weapon));
+				{ std::vector<int> rv = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits() - _unit->getActionTUs(BA_AIMEDSHOT, action->weapon));
+				  _reachableWithAttack = std::unordered_set<int>(rv.begin(), rv.end()); }
 			}
 			else
 			{
 				_rifle = true;
-				_reachableWithAttack = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits() - _unit->getActionTUs(BA_SNAPSHOT, action->weapon));
+				{ std::vector<int> rv = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits() - _unit->getActionTUs(BA_SNAPSHOT, action->weapon));
+				  _reachableWithAttack = std::unordered_set<int>(rv.begin(), rv.end()); }
 			}
@@ -208,7 +212,8 @@
 			_melee = true;
-			_reachableWithAttack = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits() - _unit->getActionTUs(BA_HIT, action->weapon));
+			{ std::vector<int> rv = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits() - _unit->getActionTUs(BA_HIT, action->weapon));
+			  _reachableWithAttack = std::unordered_set<int>(rv.begin(), rv.end()); }
 		}

 	// All std::find() calls on _reachable and _reachableWithAttack become .count():

@@ -612,1 +617,1 @@
-			std::find(_reachableWithAttack.begin(), _reachableWithAttack.end(), _save->getTileIndex(pos))  == _reachableWithAttack.end())
+			_reachableWithAttack.count(_save->getTileIndex(pos)) == 0)
@@ -902,1 +907,1 @@
-		if (std::find(_reachable.begin(), _reachable.end(), _save->getTileIndex(_escapeAction->target))  == _reachable.end())
+		if (_reachable.count(_save->getTileIndex(_escapeAction->target)) == 0)
@@ -1165,1 +1170,1 @@
-				if (_save->getTile(checkPath) == 0 || std::find(_reachable.begin(), _reachable.end(), _save->getTileIndex(checkPath))  == _reachable.end())
+				if (_save->getTile(checkPath) == 0 || _reachable.count(_save->getTileIndex(checkPath)) == 0)
@@ -1462,1 +1467,1 @@
-			std::find(_reachableWithAttack.begin(), _reachableWithAttack.end(), _save->getTileIndex(pos))  == _reachableWithAttack.end())
+			_reachableWithAttack.count(_save->getTileIndex(pos)) == 0)
@@ -2096,1 +2101,2 @@
-			_reachableWithAttack = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits() - _unit->getActionTUs(BA_HIT, meleeWeapon));
+			{ std::vector<int> rv = _save->getPathfinding()->findReachable(_unit, _unit->getTimeUnits() - _unit->getActionTUs(BA_HIT, meleeWeapon));
+			  _reachableWithAttack = std::unordered_set<int>(rv.begin(), rv.end()); }