------
## 最终结论
```python
def is_escape_possible(blocked, source, target):
    if not blocked:
        return True

    blocked_set = set(map(tuple, blocked))
    
    def bfs(start, end):
        queue = [start]
        visited = set()
        visited.add(tuple(start))
        
        directions = [(1, 0), (-1, 0), (0, 1), (0, -1)]
        
        while queue and len(visited) < 20000:
            x, y = queue.pop(0)
            
            if [x, y] == end:
                return True
            
            for dx, dy in directions:
                nx, ny = x + dx, y + dy
                
                if 0 <= nx < 10**6 and 0 <= ny < 10**6 and (nx, ny) not in visited and (nx, ny) not in blocked_set:
                    visited.add((nx, ny))
                    queue.append([nx, ny])
        
        return len(visited) >= 20000
    
    return bfs(source, target) and bfs(target, source)

# Example usage
blocked1 = [[0,1],[1,0]]
source1 = [0,0]
target1 = [0,2]
print(is_escape_possible(blocked1, source1, target1)) # Output: False

blocked2 = []
source2 = [0,0]
target2 = [999999,999999]
print(is_escape_possible(blocked2, source2, target2)) # Output: True
```