Algorithm 3: Hierarchical Void Repair Strategy

Input: Void Node $n_{void}$, Data Packet P

1: // Level 1: Intra-medium Adjustment (Optical)

2: $\mathrm{IF} (Medium=Optical$$) \mathrm{AND} (Cost(Ne{w}_{Angle})<Threshold$) THEN

3:   Adjust Divergence Angle and Retransmit P; RETURN Success

4: END IF

5: // Level 2: Cross-medium Jumping (Acoustic)

6: Calculate CDUE for all acoustic neighbors using Equation (35)

7: $\mathrm{IF} max(CDUE)>0$ THEN

8:   Switch to Acoustic Mode; Forward P to best neighbor; RETURN Success

9: END IF

10: // Level 3: Path Backtracking

11: $\mathrm{Send} Backtrac{k}_{Msg}$ $\mathrm{to} Previou{s}_{Hop}$

12: $Previou{s}_{Hop}$ selects new path using Backtrack Utility Equation (39)

13: $\mathrm{IF} Pat{h}_{Found}$ THEN RETURN Success

14: // Level 4: AUV-Assisted Repair

15: Request AUV assistance

16: AUV calculates Optimal Position using PSO Equations (41)–(43)

17: AUV performs Relay or Deployment based on Cost Equation (46); RETURN Success