From 57d2fe1409fe334d2767a9b711626577688393d7 Mon Sep 17 00:00:00 2001
From: heimoshuiyu <heimoshuiyu@gmail.com>
Date: Tue, 13 Apr 2021 19:57:33 +0800
Subject: [PATCH] week6 merge and insertion sort

---
 week6/T6.c | 151 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 week6/T6.h |  27 ++++++++++
 2 files changed, 178 insertions(+)
 create mode 100644 week6/T6.c
 create mode 100644 week6/T6.h

diff --git a/week6/T6.c b/week6/T6.c
new file mode 100644
index 0000000..9d39d45
--- /dev/null
+++ b/week6/T6.c
@@ -0,0 +1,151 @@
+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * Week_6
+ * InsertionSort and MergeSort
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "T6.h"
+
+int main() {
+	/* size of test data */
+	int size = 100000;
+
+	int *A;
+	clock_t start, end;
+
+	printf("Allocating test data space...\n");
+	A = (int *)malloc(sizeof(int) * size);
+	if (A == NULL) {
+		printf("Fatal: can not allocate A space\n");
+		exit(1);
+	}
+
+	printf("Generating random integer...\n");
+	for (int i = 0; i < size; i++) {
+		A[i] = rand();
+	}
+
+	printf("Testing merge sort...\n");
+	start = clock();
+	MergeSort(A, 0, size - 1);
+	end = clock();
+	PrintClockInterval(start, end);
+
+	printf("Checking result... %s\n", Check(A, size) ? "pass" : "fail");
+
+	printf("Generating random integer...\n");
+	for (int i = 0; i < size; i++) {
+		A[i] = rand();
+	}
+
+	printf("Testing insertion sort...\n");
+	start = clock();
+	InsertionSort(A, size);
+	end = clock();
+	PrintClockInterval(start, end);
+
+	printf("Checking result... %s\n", Check(A, size) ? "pass" : "fail");
+
+	return 0;
+}
+
+bool Check(int *A, int size) {
+	if (size == 1) {
+		return true;
+	}
+	for (int i = 0; i < size - 1; i++) {
+		if (A[i] > A[i + 1]) {
+			/* if found, return immeditily */
+			return false;
+		}
+	}
+	return true;
+}
+
+void MergeSort(int *A, int left, int right) {
+	/* alloce space */
+	int *tmp = (int *)malloc(sizeof(int) * (right - left + 1));
+	if (tmp == NULL) {
+		printf("Fatal: can not allocate space\n");
+		exit(1);
+	}
+
+	/* real merge function */
+	_MergeSort(A, tmp, left, right);
+
+	free(tmp);
+}
+
+void _MergeSort(int *A, int *tmp, int left, int right) {
+	int center;
+	if (left < right) {
+		center = (left + right) / 2;
+		_MergeSort(A, tmp, left, center);
+		_MergeSort(A, tmp, center + 1, right);
+		Merge(A, tmp, left, center + 1, right);
+	}
+}
+
+void Merge(int *A, int *tmp, int lpos, int rpos, int rightEnd) {
+	int i, leftEnd, num, tmpPos;
+
+	/* lpos -> leftEnd -> rpos -> rightEnd */
+	leftEnd = rpos - 1;
+	tmpPos = lpos;
+	num = rightEnd - lpos + 1;
+
+	/* main loop */
+	while (lpos <= leftEnd && rpos <= rightEnd) {
+		if (A[lpos] <= A[rpos]) {
+			tmp[tmpPos++] = A[lpos++];
+		} else {
+			tmp[tmpPos++] = A[rpos++];
+		}
+	}
+
+	/* copy rest of first half */
+	while (lpos <= leftEnd) {
+		tmp[tmpPos++] = A[lpos++];
+	}
+	/* copy rest of second half */
+	while (rpos <= rightEnd) {
+		tmp[tmpPos++] = A[rpos++];
+	}
+
+	/* copy tmp array back */
+	for (i = 0; i < num; i++, rightEnd--) {
+		A[rightEnd] = tmp[rightEnd];
+	}
+}
+
+void InsertionSort(int *A, int n) {
+	int j, p;
+
+	int tmp;
+
+	/* loop of p from 1 to n */
+	for (p = 1; p < n; p++) {
+
+		/* store A[p] */
+		tmp = A[p];
+
+		/* loop of j from p to 0 or
+		 * until A[j-1] <= A[p] */
+		for (j = p; j > 0 && A[j - 1] > tmp; j--) {
+			/* move */
+			A[j] = A[j - 1];
+		}
+
+		/* insert tmp to right position */
+		A[j] = tmp;
+	}
+}
+
+void PrintClockInterval(clock_t start, clock_t end) {
+	printf("Time cost is %ld ms\n", (end - start) / (CLOCKS_PER_SEC / 1000));
+}
diff --git a/week6/T6.h b/week6/T6.h
new file mode 100644
index 0000000..891fcbc
--- /dev/null
+++ b/week6/T6.h
@@ -0,0 +1,27 @@
+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * Week_6
+ * InsertionSort and MergeSort
+ */
+
+#include <stdbool.h>
+#include <time.h>
+
+/* insertion sort array A, with size n */
+void InsertionSort(int *A, int n);
+
+/* merge sort array A, start at left, end at right */
+void MergeSort(int *A, int left, int right);
+
+/* real merge sort function */
+void _MergeSort(int *A, int *tmp, int left, int right);
+
+/* merge function used in merge short */
+void Merge(int *A, int *tmp, int lpos, int rpos, int rend);
+
+/* check a sorted array */
+bool Check(int *A, int size);
+
+/* print one line to stdout about interval in ms */
+void PrintClockInterval(clock_t start, clock_t end);