Added _789.java (#29)

Author: varunu28

README.md

@@ -61,6 +61,7 @@ Your ideas/fixes/algorithms are more than welcome!
 |799|[Champagne Tower](https://leetcode.com/problems/champagne-tower/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_799.java) | O(r^2) or O(1) | O(r^2) or O(1) | |Medium|
 |796|[Rotate String](https://leetcode.com/problems/rotate-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_796.java) | O(n) | O(1) | |Easy|
 |791|[Custom Sort String](https://leetcode.com/problems/custom-sort-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_791.java) | O(n+m) | O(1) | |Medium|
+|789|[Escape The Ghosts](https://leetcode.com/problems/escape-the-ghosts/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_789.java) | O(n) | O(1) | |Medium| Math|
 |788|[Rotated Digits](https://leetcode.com/problems/rotated-digits/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_788.java) | O(n*m) | O(1) | |Easy|
 |784|[Letter Case Permutation](https://leetcode.com/problems/letter-case-permutation/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_784.java) | O(n*2^n) | O(n*2^n) | |Easy|
 |783|[Minimum Distance Between BST Nodes](https://leetcode.com/problems/minimum-distance-between-bst-nodes/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_783.java) | O(n) | O(h) | |Easy|

src/main/java/com/fishercoder/solutions/_789.java

@@ -0,0 +1,38 @@
+package com.fishercoder.solutions;
+
+/**
+ * You are playing a simplified Pacman game. You start at the point (0, 0), and your destination is
+ * (target[0], target[1]). There are several ghosts on the map, the i-th ghost starts at (ghosts[i][0], ghosts[i][1]).
+ *
+ * Each turn, you and all ghosts simultaneously *may* move in one of 4 cardinal directions: north, east, west, or
+ * south, going from the previous point to a new point 1 unit of distance away.
+ *
+ * You escape if and only if you can reach the target before any ghost reaches you (for any given moves the ghosts
+ * may take.)  If you reach any square (including the target) at the same time as a ghost, it doesn't count as an
+ * escape.
+ *
+ * Return True if and only if it is possible to escape.
+ */
+
+public class _789 {
+
+    public static class Solution {
+        public boolean escapeGhosts(int[][] ghosts, int[] target) {
+            int[] currPos = {0, 0};
+            int selfDist = getDist(currPos, target);
+
+            for (int[] ghost : ghosts) {
+                int ghostDist = getDist(ghost, target);
+                if (ghostDist <= selfDist) {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
+        private int getDist(int[] p1, int[] p2) {
+            return Math.abs(p1[0] - p2[0]) + Math.abs(p1[1] - p2[1]);
+        }
+    }
+}

src/test/java/com/fishercoder/_789Test.java

@@ -0,0 +1,36 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._789;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Created by varunu28 on 1/01/19.
+ */
+
+public class _789Test {
+    private static _789.Solution test;
+
+    @BeforeClass
+    public static void setup() {
+        test = new _789.Solution();
+    }
+
+
+    @Test
+    public void test1() {
+        assertEquals(true, test.escapeGhosts(new int[][]{{1, 0}, {0, 3}}, new int[]{0, 1}));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(false, test.escapeGhosts(new int[][]{{1, 0}}, new int[]{2, 0}));
+    }
+
+    @Test
+    public void test3() {
+        assertEquals(false, test.escapeGhosts(new int[][]{{2, 0}}, new int[]{1, 0}));
+    }
+}