1036. Escape a Large Maze

class Solution {
    private int[][] dirs = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
    
    public boolean isEscapePossible(int[][] blocked, int[] source, int[] target) {
        Set<String> block = new HashSet<>();
        for (int[] p : blocked) {
            block.add(p[0] + "->" + p[1]);
        }
        
        return dfs(source, target, source, block, new HashSet<>()) && 
            dfs(target, source, target, block, new HashSet<>());
    }
    
    private boolean dfs(int[] source, int[] target, int[] cur, 
        Set<String> block, Set<String> visited) {
        if (cur[0] == target[0] && cur[1] == target[1]) return true;
        if (Math.abs(source[0] - cur[0]) + Math.abs(source[1] - cur[1]) > 200) return true;
        
        visited.add(cur[0] + "->" + cur[1]);
        for (int[] d : dirs) {
            int r = d[0] + cur[0];
            int c = d[1] + cur[1];
            String str = r + "->" + c;
            
            if (r >= 0 && r < 1000000 && 
               c >= 0 && c < 1000000 && 
               !block.contains(str) && 
               !visited.contains(str)) {
                if (dfs(source, target, new int[]{r, c}, block, visited)) return true;
            }
        }
        
        return false;
    }
}