diff --git a/thu_dsa/chp12/shellsort.cpp b/thu_dsa/chp12/shellsort.cpp
new file mode 100644
index 0000000..d443cc0
--- /dev/null
+++ b/thu_dsa/chp12/shellsort.cpp
@@ -0,0 +1,110 @@
+#include "../chp2/Vector.h"
+#include <iostream>
+#include <cassert>
+#include <random>
+#include <ctime>
+
+#define SEDGEWICK
+#define SCALE     65536
+#define LOOP      16
+
+using namespace std;
+
+Vector<int> shellSeq;
+time_t test_shellsort();
+
+void init_shell_seq(int n){
+#ifdef INSERTSORT
+	shellSeq.push_back(1);
+#else
+#ifdef SHELLSEQ
+	shellSeq.push_back(1);
+	int ix = 0;
+	while ((shellSeq[ix] << 1) < n) shellSeq.push_back(shellSeq[ix++] << 1);
+#else
+#ifdef PAPERNOV
+	int ix = 0, curr = 2;
+	while (curr - 1 < n) {
+		shellSeq.push_back(curr - 1);
+		curr = curr << 1;
+	}
+#else //SEDGEWICK
+	int power2i = 1, power4i = 1;                //stand for 2^k and 4^k
+	int power2j = 4, power4j = 16;
+	int seqi = 1, seqj = 5;
+	while(seqi < n || seqj < n){
+		if (seqj < seqi) {
+			shellSeq.push_back(seqj);
+			power2j = power2j << 1;
+			power4j = power4j << 2;
+			seqj = power4j - 3 * power2j + 1;
+		}
+		else if (seqi < seqj) {
+			shellSeq.push_back(seqi);
+			power2i = power2i << 1;
+			power4i = power4i << 2;
+			seqi = 9 * power4i - 9 * power2i + 1;
+		}
+		else{
+			shellSeq.push_back(seqi);
+			power2i = power2i << 1;
+			power4i = power4i << 2;
+			seqi = 9 * power4i - 9 * power2i + 1;
+			power2j = power2j << 1;
+			power4j = power4j << 2;
+			seqj = power4j - 3 * power2j + 1;
+		}
+	}
+#endif
+#endif
+#endif
+}
+
+void shellSort(int* src, int n){
+	//init_shell_seq(n);
+	int step, pos, curr;
+	for(int ix = shellSeq.getSize() - 1; ix >= 0; --ix){
+		step = shellSeq[ix];
+		for(int jx = step; jx != n; ++jx){
+			pos = jx - step;
+			curr = src[jx];
+			while (pos >= 0 && curr < src[pos]){
+				//swap src[jx] and src[pos]
+				src[pos + step] = src[pos];
+				pos -= step;
+			}
+			src[pos + step] = curr;
+		}
+	}
+}
+
+int main(){
+	srand((int)time(NULL));
+	time_t time = 0;
+	cout << "begin tests ..." << endl;
+
+	for(int ix = 0; ix < LOOP; ++ix)
+		time += test_shellsort();
+	cout << "test_shellsort passed, running time: " << time / LOOP << endl;
+
+	cout << "all tests passed." << endl;
+	system("pause");
+	return 0;
+}
+
+time_t test_shellsort(){
+	int *src = new int[SCALE];
+	time_t begin, end;
+	for (int ix = 0; ix != SCALE; ++ix)
+		src[ix] = rand();
+	
+	init_shell_seq(SCALE);
+	begin = clock();
+	shellSort(src, SCALE);
+	end = clock();
+
+	for (int ix = 1; ix != SCALE; ++ix)
+		assert(src[ix - 1] <= src[ix]);
+
+	return end - begin;
+}