add 1545

fishercoder1534 · fishercoder1534 · commit df995aae8f41 · 2020-08-09T06:26:10.000-07:00
diff --git a/README.md b/README.md
@@ -8,6 +8,7 @@ _If you like this project, please leave me a star._ &#9733;
 
 |  #  |      Title     |   Solutions   | Video  | Difficulty  | Tag                   
 |-----|----------------|---------------|--------|-------------|-------------
+|1545|[Find Kth Bit in Nth Binary String](https://leetcode.com/problems/find-kth-bit-in-nth-binary-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1545.java) | |Medium|String|
 |1544|[Make The String Great](https://leetcode.com/problems/make-the-string-great/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1544.java) | |Easy|String, Stack|
 |1541|[Minimum Insertions to Balance a Parentheses String](https://leetcode.com/problems/minimum-insertions-to-balance-a-parentheses-string/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1541.java) | |Medium|String, Stack|
 |1539|[Kth Missing Positive Number](https://leetcode.com/problems/kth-missing-positive-number/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_1539.java) | |Easy|Array, HashTable|
diff --git a/src/main/java/com/fishercoder/solutions/_1545.java b/src/main/java/com/fishercoder/solutions/_1545.java
@@ -0,0 +1,35 @@
+package com.fishercoder.solutions;
+
+public class _1545 {
+    public static class Solution1 {
+        public char findKthBit(int n, int k) {
+            String[] strings = new String[n];
+            strings[0] = "0";
+            for (int i = 1; i < n; i++) {
+                strings[i] = formString(strings[i - 1]);
+            }
+            return strings[n - 1].charAt(k - 1);
+        }
+
+        private String formString(String str) {
+            return str + "1" + reverse(invert(str));
+        }
+
+        private String reverse(String str) {
+            StringBuilder sb = new StringBuilder();
+            return sb.append(str).reverse().toString();
+        }
+
+        private String invert(String str) {
+            StringBuilder sb = new StringBuilder();
+            for (char c : str.toCharArray()) {
+                if (c == '1') {
+                    sb.append('0');
+                } else {
+                    sb.append('1');
+                }
+            }
+            return sb.toString();
+        }
+    }
+}
diff --git a/src/test/java/com/fishercoder/_1545Test.java b/src/test/java/com/fishercoder/_1545Test.java
@@ -0,0 +1,37 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._1545;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _1545Test {
+    private static _1545.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _1545.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals('0', solution1.findKthBit(3, 1));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals('1', solution1.findKthBit(4, 11));
+    }
+
+    @Test
+    public void test3() {
+        assertEquals('0', solution1.findKthBit(1, 1));
+    }
+
+    @Test
+    public void test4() {
+        assertEquals('1', solution1.findKthBit(2, 3));
+    }
+
+}
