add reward discount

Project/Assets/ML-Agents/Examples/PushBlock/Prefabs/ZombiePushBlockDeathCollabArea.prefab

   UseRandomBlockRotation: 1
   UseRandomBlockPosition: 1
   UseTeamManager: 1
+  UseTeamReward: 1
+  TeamRewardDiscount: 0.995
 --- !u!1 &4478780967772121042
 GameObject:
   m_ObjectHideFlags: 0

Project/Assets/ML-Agents/Examples/PushBlock/Scripts/PushBlockTeamManager.cs

 using System.Linq;
 using Unity.MLAgents.Extensions.Teams;
 using Unity.MLAgents.Sensors;
+using System;
-    Dictionary<Agent, bool> m_AgentDone = new Dictionary<Agent, bool> { };
+    float m_RewardDiscount = 1;
+
+    // -1 means not done
+    Dictionary<Agent, int> m_AgentDoneStep = new Dictionary<Agent, int> { };
-        m_AgentDone[agent] = false;
+        m_AgentDoneStep[agent] = -1;
-        m_AgentDone[agent] = true;
+        m_AgentDoneStep[agent] = agent.StepCount;
-        foreach (var agent in m_AgentDone.Keys.ToList())
+        foreach (var agent in m_AgentDoneStep.Keys.ToList())
-            if (m_AgentDone[agent])
+            if (m_AgentDoneStep[agent] >= 0)
-                m_AgentDone[agent] = false;
+                m_AgentDoneStep[agent] = -1;
             }
         }
     }
-        foreach (var agent in m_AgentDone.Keys)
+        int maxAgentStep = m_AgentDoneStep.Values.Max();
+        foreach (var agent in m_AgentDoneStep.Keys)
-            if (m_AgentDone[agent])
+            if (m_AgentDoneStep[agent] >= 0)
-                agent.AddRewardAfterDeath(reward);
+                agent.AddRewardAfterDeath(reward * (float)Math.Pow(m_RewardDiscount, maxAgentStep - m_AgentDoneStep[agent]));
             }
             else
             {
+    }
+
+    public void SetRewardDiscount(float discountRate)
+    {
+        m_RewardDiscount = discountRate;
     }
 }

Project/Assets/ML-Agents/Examples/PushBlock/Scripts/ZombiePushBlockDeathEnvController.cs

     public bool UseRandomBlockPosition = true;
     public bool UseTeamManager = true;
     public bool UseTeamReward = true;
-    // public bool DiscountTeamReward = true;
+    public float TeamRewardDiscount = 1;
     PushBlockSettings m_PushBlockSettings;
 
     private BaseTeamManager m_TeamManager;
             if (UseTeamReward)
             {
                 m_TeamManager = new PushBlockTeamManager();
+                var pushManager = (PushBlockTeamManager)m_TeamManager;
+                pushManager.SetRewardDiscount(TeamRewardDiscount);
             }
             else
             {