diff --git a/thu_dsa/chp2/Vector.h b/thu_dsa/chp2/Vector.h
index 183d244..8ae5e9a 100644
--- a/thu_dsa/chp2/Vector.h
+++ b/thu_dsa/chp2/Vector.h
@@ -107,6 +107,18 @@ void Vector<T>::swap(T &one, T &two){
 	two = temp;
 }
 
+template <typename T>
+void Vector<T>::merge(int lo, int mid, int hi){
+	int leftLen = mid - lo;
+	T* tmp = new T[leftLen];
+	for (int ix = 0; ix != leftLen; ++ix) tmp[ix] = _elem[ix + lo];
+
+	for (int pos = lo, ix = 0, jx = mid; ix != leftLen;) {
+		if (hi <= jx || tmp[ix] <= _elem[jx]) _elem[pos++] = tmp[ix++];
+		if (jx < hi && _elem[jx] < tmp[ix])  _elem[pos++] = _elem[jx++];
+	}
+}
+
 template <typename T>
 int Vector<T>::bubble(int lo, int hi){
 	int lastSwap = 0;
@@ -189,6 +201,20 @@ int Vector<T>::binary_search(T const &elem, int lo, int hi){
 	return lo - 1;
 }
 
+template <typename T>
+int Vector<T>::interpolation_search(T const &elem, int lo, int hi){
+	int mid;
+	while(lo < hi){
+		mid = lo + (elem - _elem[lo])*(hi - lo) / (_elem[hi] - _elem[lo]);
+		if (mid < lo || mid >= hi) break;
+
+		if (elem < _elem[mid]) hi = mid;
+		else if (_elem[mid] < elem) lo = mid + 1;
+		else return mid;
+	}
+	return lo - 1;
+}
+
 template <typename T>
 int Vector<T>::unordered(int lo, int hi){
 	int reversed = 0;
@@ -286,4 +312,14 @@ void Vector<T>::bubbleSort(int lo, int hi){
 	while (lo < (hi = bubble(lo, hi)));
 }
 
+template <typename T>
+void Vector<T>::mergeSort(int lo, int hi){
+	if (hi - lo < 2) return;
+
+	int mid = (lo + hi) >> 1;
+	mergeSort(lo, mid);
+	mergeSort(mid, hi);
+	merge(lo, mid, hi);
+}
+
 #endif
diff --git a/thu_dsa/chp2/testVector.cpp b/thu_dsa/chp2/testVector.cpp
index 21a9385..fca246f 100644
--- a/thu_dsa/chp2/testVector.cpp
+++ b/thu_dsa/chp2/testVector.cpp
@@ -17,8 +17,10 @@ void test_delete();
 void test_find();
 void test_unique();
 void test_search();
+void test_search_performance();
 void test_map();
 void test_bubbleSort();
+void test_mergeSort();
 
 int main(){
 	test_constructor();
@@ -28,7 +30,9 @@ int main(){
 	test_find();
 	test_unique();
 	test_search();
+	test_search_performance();
 	test_bubbleSort();
+	test_mergeSort();
 	test_map();
 
 	system("pause");
@@ -175,6 +179,11 @@ void test_search(){
 	assert(v.fib_search(14, 9, v.getSize()) == 8);
 	assert(v.fib_search(1, 0, v.getSize()) == -1);
 
+	//test interpolation_search
+	assert(v.interpolation_search(14, 0, v.getSize()) == 7);
+	assert(v.interpolation_search(14, 9, v.getSize()) == 8);
+	assert(v.interpolation_search(1, 0, v.getSize()) == -1);
+
 	//test binary_search
 	assert(v.binary_search(14, 0, v.getSize()) == 7);
 	assert(v.binary_search(15, 0, v.getSize()) == 7);
@@ -189,6 +198,49 @@ void test_search(){
 	cout << "test passed." << endl;
 }
 
+void test_search_performance(){
+	cout << "run test_search_performance..." << endl;
+	srand((unsigned)time(NULL));
+	Vector<int> v1;
+	for (int ix = 0; ix != ELEMENT_NUM; ++ix)
+		v1.push_back(rand());
+	v1.mergeSort();
+
+	//test binary search
+	cout << "run binary_search...";
+	clock_t begin = clock();
+	for(int ix = 0; ix != NUMOFLOOPS; ++ix)
+		assert(v1.binary_search(v1[824], 0, v1.getSize()) == 824);
+	clock_t end = clock();
+	cout << "Running time: " << end - begin << endl;
+
+	//test plain old search
+	cout << "run plain old search...";
+	begin = clock();
+	for (int ix = 0; ix != NUMOFLOOPS; ++ix)
+		assert(v1.search(v1[824], 0, v1.getSize()) == 824);
+	end = clock();
+	cout << "Running time: " << end - begin << endl;
+
+	//test fib search
+	cout << "run fib_search...";
+	begin = clock();
+	for (int ix = 0; ix != NUMOFLOOPS; ++ix)
+		assert(v1.fib_search(v1[824], 0, v1.getSize()) == 824);
+	end = clock();
+	cout << "Running time: " << end - begin << endl;
+
+	//test interpolation search
+	cout << "run binary_search...";
+	begin = clock();
+	for (int ix = 0; ix != NUMOFLOOPS; ++ix)
+		assert(v1.interpolation_search(v1[824], 0, v1.getSize()) == 824);
+	end = clock();
+	cout << "Running time: " << end - begin << endl;
+
+	cout << "test passed." << endl;
+}
+
 void test_bubbleSort(){
 	cout << "run test_bubbleSort...\n";
 	int A[] = { 2,3,4,6,1,0,9,8,7,5 };
@@ -216,6 +268,33 @@ void test_bubbleSort(){
 	cout << "test passed." << endl;
 }
 
+void test_mergeSort(){
+	cout << "run test_mergeSort..." << endl;
+	int A[] = { 2,3,4,6,1,0,9,8,7,5 };
+	Vector<int> v(A, 10);
+	assert(v.unordered() == 5);
+
+	v.mergeSort();
+	assert(v.unordered() == 0);
+	for (int ix = 0; ix != 10; ++ix)
+		assert(v[ix] == ix);
+
+	srand((unsigned)time(NULL));
+	Vector<int> v1;
+	for (int ix = 0; ix != ELEMENT_NUM; ++ix)
+		v1.push_back(rand());
+	assert(v1.getSize() == ELEMENT_NUM);
+	assert(v1.unordered() != 0);
+
+	clock_t begin = clock();
+	v1.mergeSort();
+	clock_t end = clock();
+	assert(v.unordered() == 0);
+	cout << "Running time: " << end - begin << endl;
+
+	cout << "test passed." << endl;
+}
+
 template <typename T>
 void Increase(T & elem) { ++elem; }
 void test_map(){