solve: No.295

Author: BaffinLee

201-300/295. Find Median from Data Stream.md

@@ -71,14 +71,61 @@ medianFinder.findMedian(); // return 2.0
 ## Solution
 
 ```javascript
-
+var MedianFinder = function() {
+    this.arr = [];
+};
+
+/** 
+ * @param {number} num
+ * @return {void}
+ */
+MedianFinder.prototype.addNum = function(num) {
+    if (!this.arr.length) {
+        this.arr.push(num);
+        return;
+    }
+    var left = 0;
+    var right = this.arr.length - 1;
+    while (left <= right) {
+        if (left === right) {
+            this.arr.splice(this.arr[left] >= num ? left : (left + 1), 0, num);
+            return;
+        }
+        var mid = left + Math.floor((right - left) / 2);
+        if (this.arr[mid] === num) {
+            left = mid;
+            right = mid;
+        } else if (this.arr[mid] > num) {
+            right = mid;
+        } else {
+            left = mid + 1;
+        }
+    }
+};
+
+/**
+ * @return {number}
+ */
+MedianFinder.prototype.findMedian = function() {
+    return this.arr.length % 2
+        ? this.arr[(this.arr.length - 1) / 2]
+        : (this.arr[this.arr.length / 2] + this.arr[this.arr.length / 2 - 1]) / 2;
+        
+};
+
+/** 
+ * Your MedianFinder object will be instantiated and called as such:
+ * var obj = new MedianFinder()
+ * obj.addNum(num)
+ * var param_2 = obj.findMedian()
+ */
 ```
 
 **Explain:**
 
-nope.
+Binary search.
 
 **Complexity:**
 
-* Time complexity : O(n).
+* Time complexity : O(n * log(n)).
 * Space complexity : O(n).