Merge pull request doocs#301 from AudiVehicle/master

add solution for leetcode 1036

Author: yanglbme

solution/1000-1099/1036.Escape a Large Maze/Solution.java

@@ -0,0 +1,48 @@
+class Solution {
+
+    private static final int[] dx = {0, 0, -1, 1};
+    private static final int[] dy = {1, -1, 0, 0};
+
+
+    public boolean isEscapePossible(int[][] blocked, int[] source, int[] target) {
+        if (blocked.length < 2) {
+            return Boolean.TRUE;
+        }
+
+        return walk(blocked, source, target) && walk(blocked, target, source);
+    }
+
+    private Boolean walk(int[][] blocked, int[] source, int[] target) {
+        int N = 1000000;
+
+        Set<Pair<Integer, Integer>> visitSet = new HashSet<>();
+        Queue<Pair<Integer, Integer>> queue = new LinkedList<>();
+
+        Pair<Integer, Integer> start = new Pair<>(source[0], source[1]);
+        queue.add(start);
+        visitSet.add(start);
+
+        Set<Pair> blockedSet = Arrays.stream(blocked).map(item -> new Pair(item[0], item[1])).collect(Collectors.toSet());
+
+        while (!queue.isEmpty()) {
+            Pair<Integer, Integer> top = queue.poll();
+            Integer x = top.getKey();
+            Integer y = top.getValue();
+
+            for (int i = 0; i < 4; i++) {
+                int newY = y + dy[i];
+                int newX = x + dx[i];
+                Pair<Integer, Integer> pair = new Pair<>(newX, newY);
+                if (newX < 0 || newY < 0 || newX >= N || newY >= N || visitSet.contains(pair) || blockedSet.contains(pair)) {
+                    continue;
+                }
+                queue.add(pair);
+                visitSet.add(pair);
+                if (queue.size() >= blocked.length || (newX == target[0] && newY == target[1])) {
+                    return Boolean.TRUE;
+                }
+            }
+        }
+        return Boolean.FALSE;
+    }
+}