java: add «374. Guess Number Higher or Lower»

Signed-off-by: Matej Focko <me@mfocko.xyz>

java/guess-number-higher-or-lower.java

@@ -0,0 +1,41 @@
+/**
+ * Forward declaration of guess API.
+ *
+ * @param num your guess
+ * @return -1 if num is higher than the picked number 1 if num is lower than the picked number
+ *     otherwise return 0 int guess(int num);
+ */
+class Solution extends GuessGame {
+  private enum Response {
+    Smaller(-1),
+    Exact(0),
+    Bigger(1);
+
+    public final int value;
+
+    private Response(int value) {
+      this.value = value;
+    }
+  }
+
+  public int guessNumber(int n) {
+    int lower = 1;
+    int upper = n;
+
+    while (true) {
+      var mid = lower + (upper - lower) / 2;
+
+      int response = guess(mid);
+      if (response == Response.Exact.value) {
+        return mid;
+      } else if (response == Response.Smaller.value) {
+        upper = mid - 1;
+      } else if (response == Response.Bigger.value) {
+        lower = mid + 1;
+      } else {
+        // invalid response
+        return -1;
+      }
+    }
+  }
+}