Update 74-Search_A-2D-Matrix.java to binary search instead of linear

java/74-Search-A-2D-Matrix.java

@@ -1,16 +1,22 @@
 class Solution {
     public boolean searchMatrix(int[][] matrix, int target) {
-        int i = 0;
-        int j = matrix[0].length - 1;
-        while(i >= 0 && i <= matrix.length - 1 && j >= 0 && j <= matrix[0].length - 1){
-            if(matrix[i][j] == target){
-                return true;
-            } else if (matrix[i][j] > target){
-                j--;
-            } else {
-                i++;
-            }
+        int lrow = 0;
+        int rrow = matrix.length - 1;
+        int n = 0;
+
+        while (lrow < rrow) {
+            n = (lrow + rrow) / 2;
+            if (matrix[n][0] > target)
+                rrow = n;
+            else if (matrix[n][matrix[0].length - 1] < target)
+                lrow = n + 1;
+            else
+                break;
         }
-        return false;
+
+        if (Arrays.binarySearch(matrix[(lrow + rrow) / 2], target) >= 0)
+            return true;
+        else
+            return false;
     }
 }