Complete Graph-1

TheMaze.java

@@ -0,0 +1,46 @@
+// O(n * m) time, O(n * m) space
+
+import java.util.*;
+
+class Solution {
+    public boolean hasPath(int[][] maze, int[] start, int[] destination) {
+        int n = maze.length;
+        int m = maze[0].length;
+
+        int[][] dirs = new int[][] {
+            {1,0},{0,1},{0,-1},{-1,0}
+        };
+        boolean[][] visited = new boolean[n][m];
+
+        Queue<int[]> q = new LinkedList<>();
+        q.offer(start);
+        visited[start[0]][start[1]] = true;
+
+        while (!q.isEmpty()) {
+            int[] curr = q.poll();
+            if (curr[0] == destination[0] && curr[1] == destination[1]) {
+                return true;
+            }
+
+            for (int[] dir : dirs) {
+                int r = dir[0] + curr[0];
+                int c = dir[1] + curr[1];
+
+                // keep moving ball until inbounds and is empty space
+                while (r >= 0 && c >= 0 && r < n && c < m && maze[r][c] == 0) {
+                    r += dir[0];
+                    c += dir[1];
+                }
+                r -= dir[0];
+                c -= dir[1];
+
+                if (!visited[r][c]) {
+                    q.offer(new int[]{r,c});
+                    visited[r][c] = true;
+                }
+
+            }
+        }
+        return false;
+    }
+}

TownJudge.java

@@ -0,0 +1,19 @@
+// O(V + E) time, O(V) space
+class Solution {
+    public int findJudge(int n, int[][] trust) {
+        int[] indegrees = new int[n+1];
+        int[] outDegrees = new int[n+1];
+
+        for (int[] tr: trust) {
+            outDegrees[tr[0]]++;
+            indegrees[tr[1]]++;
+        }
+
+        for (int i = 1; i <= n; i++) {
+            if (indegrees[i] == n-1 && outDegrees[i] == 0) {
+                return i;
+            }
+        }
+        return -1;
+    }
+}