update 3637 mod solution

java/search/BinarySearch3637.java

@@ -15,33 +15,34 @@ public class BinarySearch3637 {
             a.put(Integer.parseInt(args[i]));
         }
 
-        int start = searchIterativeDecreasing(x, a);
+        System.out.println(rightBound(x, a) - leftBound(x, a));
-        int end = searchIterativeIncreasing(x, a.getReversed());
-        if (a.get(start) != x) {
-            System.out.println(0);
-        } else {
-            System.out.println(end - start);
-        }
-    }
-
-    static int searchIterativeIncreasing(int x, IntList a) {
-        if (a.getLength() == 0) {
-            return 0;
     }
 
+    static int leftBound(int x, IntList a) {
         int low = 0,
             high = a.getLength() - 1;
-
         while (low <= high) {
             int mid = low + (high - low) / 2;
+            if (a.get(mid) >= x) {
+                high = mid - 1;
+            } else {
+                low = mid + 1;
+            }
+        }
+        return low;
+    }
 
+    static int rightBound(int x, IntList a) {
+        int low = 0,
+            high = a.getLength() - 1;
+        while (low <= high) {
+            int mid = low + (high - low) / 2;
             if (a.get(mid) <= x) {
                 low = mid + 1;
             } else {
                 high = mid - 1;
             }
         }
-
         return low;
     }
 

java/search/IntList.java

@@ -28,16 +28,6 @@ public class IntList {
         return idx;
     }
 
-    public IntList getReversed() {
-        IntList reverse = new IntList(new int[idx]);
-
-        for (int i = idx - 1; i >= 0; i--) {
-            reverse.put(list[i]);
-        }
-
-        return reverse;
-    }
-
     public int get(int index) {
         return list[index];
     }