[Function add]

1. Add leetcode solutions with tag binary search.

Author: Seanforfun

leetcode/378. Kth Smallest Element in a Sorted Matrix.md

@@ -66,3 +66,21 @@ class Solution {
     }
 }
 ```
+
+
+### Third Time
+* Method 1: binary search 
+	```Java
+	class Solution {
+		public int mySqrt(int x) {
+			if(x == 0 || x == 1) return x;
+			int left = 1, right = x / 2;
+			while(left <= right){
+				int mid = left + (right - left) / 2;
+				if(mid > x / mid) right = mid - 1;
+				else left = mid + 1;
+			}
+			return right;
+		}
+	}
+	```

leetcode/69. Sqrt(x).md

@@ -59,3 +59,26 @@ class Solution {
     }
 }
 ```
+
+### Third Time
+* Method 1: Binary Search, AC 100%
+	```Java
+	class Solution {
+		public boolean searchMatrix(int[][] matrix, int target) {
+			if(matrix == null || matrix.length == 0 || matrix[0].length == 0) return false;
+			int height = matrix.length, width = matrix[0].length;
+			int row = 0;
+			while(row < height && target > matrix[row][width - 1]){
+				row++;
+			}
+			return row >= height ? false: bs(matrix[row], 0, width - 1, target);
+		}
+		private boolean bs(int[] nums, int low, int high, int target){
+			if(low > high) return false;
+			int mid = low + (high - low) / 2;
+			if(target == nums[mid]) return true;
+			else if(target > nums[mid]) return bs(nums, mid + 1, high, target);
+			else return bs(nums, low, mid - 1, target);
+		}
+	}
+	```