diff --git a/4.shellSort.md b/4.shellSort.md
index cfa59f5..e6d5f9c 100644
--- a/4.shellSort.md
+++ b/4.shellSort.md
@@ -69,7 +69,7 @@ def shellSort(arr):
 func shellSort(arr []int) []int {
 	length := len(arr)
 	gap := 1
-	for gap < gap/3 {
+	for gap < length/3 {
 		gap = gap*3 + 1
 	}
 	for gap > 0 {
@@ -144,3 +144,23 @@ function shellSort($arr)
     return $arr;
 }
 ```
+
+## 7. C++ 代码实现
+
+```cpp
+void shellSort(vector<int>& arr) {
+    int gap = 1;
+    while (gap < (int)arr.size() / 3) {
+    	gap = gap * 3 + 1;
+    }
+    for (; gap >= 1; gap /= 3) {
+	for (int i = 0; i < gap; ++i) {
+	    for (int j = i + gap; j < arr.size(); j += gap) {
+		for (int k = j; k - gap >= 0 && arr[k] < arr[k - gap]; k -= gap) {
+                    swap(arr[k], arr[k - gap]);
+                }
+            }
+        }
+    }
+}
+```
diff --git a/5.mergeSort.md b/5.mergeSort.md
index bf0de32..c030d8f 100644
--- a/5.mergeSort.md
+++ b/5.mergeSort.md
@@ -222,4 +222,41 @@ function merge($left, $right)
 
     return $result;
 }
-```
\ No newline at end of file
+```
+
+## 9. C++ 代码实现
+
+```cpp
+void merge(vector<int>& arr, int l, int mid, int r) {
+    int index = 0;
+    int ptrL = l;
+    int ptrR = mid;
+    static vector<int>tempary;
+    if (arr.size() > tempary.size()) {
+        tempary.resize(arr.size());
+    }
+    while (ptrL != mid && ptrR != r) {
+        if (arr[ptrL] < arr[ptrR]) {
+            tempary[index++] = arr[ptrL++];
+        } else {
+            tempary[index++] = arr[ptrR++];
+        }
+    }
+    while (ptrL != mid) {
+        tempary[index++] = arr[ptrL++];
+    }
+    while (ptrR != r) {
+        tempary[index++] = arr[ptrR++];
+    }
+    copy(tempary.begin(), tempary.begin() + index, arr.begin() + l);
+}
+void mergeSort(vector<int>& arr, int l, int r) { // sort the range [l, r) in arr
+    if (r - l <= 1) {
+        return;
+    }
+    int mid = (l + r) / 2;
+    mergeSort(arr, l, mid);
+    mergeSort(arr, mid, r);
+    merge(arr, l, mid, r);
+}
+```
diff --git a/src/pythonSortTest.py b/src/pythonSortTest.py
index ea765d2..bf092db 100644
--- a/src/pythonSortTest.py
+++ b/src/pythonSortTest.py
@@ -1,4 +1,4 @@
-'''
+'''
 # Create by LokiSharp(loki.sharp#gmail) at 2017-1-22
 '''
 
@@ -176,6 +176,34 @@ def countingSort(arr, maxValue=None):
             bucket[j] -= 1
     return arr
 
+def radix_count(exp1):
+    global list
+    n = len(list)
+    output = [0] * (n)
+    count = [0] * (10)
+    for i in range(0, n):
+        index = (list[i] / exp1)
+        count[(index) % 10] += 1
+    for i in range(1,10):
+        count[i] += count[i - 1]
+    i = n - 1
+    while i >= 0:
+        index = (list[i]/exp1)
+        output[count[(index) % 10] - 1] = list[i]
+        count[(index) % 10] -= 1
+        i -= 1
+    i = 0
+    for i in range(0,len(list)):
+        list[i] = output[i]
+
+def radixSort():
+    global list
+    max1 = max(list)
+    exp = 1
+    while max1 / exp > 0:
+        radix_count(exp)
+        exp *= 10
+
 
 if __name__ == '__main__':
     sortTest(bubbleSort, TOTAL)
@@ -185,3 +213,4 @@ def countingSort(arr, maxValue=None):
     sortTest(mergeSort, TOTAL)
     sortTest(quickSort, TOTAL)
     sortTest(heapSort, TOTAL)
+    sortTest(radixSort, TOTAL)