1+ class Solution {
2+ 3+ private static final int [] dx = {0 , 0 , -1 , 1 };
4+ private static final int [] dy = {1 , -1 , 0 , 0 };
5+ 6+ 7+ public boolean isEscapePossible (int [][] blocked , int [] source , int [] target ) {
8+ if (blocked .length < 2 ) {
9+ return Boolean .TRUE ;
10+ }
11+ 12+ return walk (blocked , source , target ) && walk (blocked , target , source );
13+ }
14+ 15+ private Boolean walk (int [][] blocked , int [] source , int [] target ) {
16+ int N = 1000000 ;
17+ 18+ Set <Pair <Integer , Integer >> visitSet = new HashSet <>();
19+ Queue <Pair <Integer , Integer >> queue = new LinkedList <>();
20+ 21+ Pair <Integer , Integer > start = new Pair <>(source [0 ], source [1 ]);
22+ queue .add (start );
23+ visitSet .add (start );
24+ 25+ Set <Pair > blockedSet = Arrays .stream (blocked ).map (item -> new Pair (item [0 ], item [1 ])).collect (Collectors .toSet ());
26+ 27+ while (!queue .isEmpty ()) {
28+ Pair <Integer , Integer > top = queue .poll ();
29+ Integer x = top .getKey ();
30+ Integer y = top .getValue ();
31+ 32+ for (int i = 0 ; i < 4 ; i ++) {
33+ int newY = y + dy [i ];
34+ int newX = x + dx [i ];
35+ Pair <Integer , Integer > pair = new Pair <>(newX , newY );
36+ if (newX < 0 || newY < 0 || newX >= N || newY >= N || visitSet .contains (pair ) || blockedSet .contains (pair )) {
37+ continue ;
38+ }
39+ queue .add (pair );
40+ visitSet .add (pair );
41+ if (queue .size () >= blocked .length || (newX == target [0 ] && newY == target [1 ])) {
42+ return Boolean .TRUE ;
43+ }
44+ }
45+ }
46+ return Boolean .FALSE ;
47+ }
48+ }
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