完成第九章测试

Author: jungor

Makefile

@@ -21,12 +21,15 @@ $(TARGET): $(addsuffix .o, $(TARGET)) $(OBJS)
 $(TEST): $(addsuffix .o, $(TEST)) $(ALLOBJS)
 	@$(CC) -o $@ $^ $(LDFLAGS)
 
+# 要么把所有源文件加到依赖；要么设为phony。
+# 否则首次生成过tags之后后续会因为已存在不再生成
 tags: $(ALLFILES)
 	@ctags -R .
 
 %.o:%.c
 	@$(CC) -o $@ -c $< $(CFLAGS) $(INCLUDEFLAGS)
 
+# 使用gcc的-MM选项自动生成各源文件的依赖
 %.d:%.c
 	@set -e; rm -f $@; $(CC) -MM $< $(INCLUDEFLAGS) > $@.$$$$; \
 	sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \

chap08/test_counting_sort.c

@@ -5,10 +5,10 @@
 #include <stdlib.h>
 
 static void test_counting_sort() {
-    int len = 10;
+    int len = 100;
     int nums[len];
     for (int i = 0; i < len; i++) {
-        nums[i] = rand() % len;
+        nums[i] = rand() % COUNTING_SORT_NUM_MAX;
     }
     counting_sort(nums, len);
     for (int i = 1; i < len; i++) {

chap09/order_statistic.c

@@ -65,13 +65,16 @@ int median_of_medians(int nums[], int begin, int end) {
             part[j] = nums[i*5+j];
         }
         int part_len = 5;
-        if (i > len / 5) {
+        if (i == parts_count-1) {
             part_len = last_part_len;
         }
+        // 这里可以直接使用插入排序确定每组的中位数
+        // 树上就是这样做而且证明这样整个算法还是最坏线性
+        // 我的理解是因为每组的大小是常数
         insertion_sort(part, part_len);
-        medians[i] = part[part_len/2];
+        medians[i] = part[(part_len-1)/2];
     }
-    int mm = linear_select(medians, 0, parts_count, parts_count/2);
+    int mm = medians[(parts_count-1)/2];
     free(medians);
     return mm;
 }
@@ -98,9 +101,9 @@ int linear_select(int nums[], int begin, int end, int i) {
     if (len == 1) {
         return nums[begin];
     }
-    // index of median_of_medians
-    int imm = median_of_medians(nums, begin, end);
-    int q = specified_partition(nums, begin, end, imm);
+    // median_of_medians
+    int mm = median_of_medians(nums, begin, end);
+    int q = specified_partition(nums, begin, end, mm);
     int left_len = q - begin;
     if (i == left_len) {
         return nums[q];

chap09/test_order_statistic.c

@@ -0,0 +1,28 @@
+#include "order_statistic.h"
+#include "test_order_statistic.h"
+#include "../utils.h"
+#include <CUnit/CUnit.h>
+#include <stdlib.h>
+
+static void test_order_statistic() {
+    int len = 100;
+    int nums[len];
+    for (int i = 0; i < len; i++) {
+        nums[i] = i;;
+    }
+    shuffle(nums, len);
+    CU_ASSERT(maximum(nums, len) == len-1);
+    CU_ASSERT(minimum(nums, len) == 0);
+    for (int i = 1; i < len; i++) {
+        CU_ASSERT(randomized_select(nums, 0, len, i) == i);
+        //CU_ASSERT(linear_select(nums, 0, len, i) == i);
+    }
+}
+
+CU_ErrorCode add_test_order_statistic() {
+    CU_pSuite pSuite = CU_add_suite("order_statistic", NULL, NULL);
+    CHECK_CU_GLOBAL();
+    CU_ADD_TEST(pSuite, test_order_statistic);
+    CHECK_CU_GLOBAL();
+    return CUE_SUCCESS;
+}

chap09/test_order_statistic.h

@@ -0,0 +1,8 @@
+#ifndef TEST_ORDER_STATISTIC_H
+#define TEST_ORDER_STATISTIC_H
+
+#include <CUnit/CUnit.h>
+
+CU_ErrorCode add_test_order_statistic();
+
+#endif

test.c

@@ -5,6 +5,7 @@
 #include "chap07/test_quick_sort.h"
 #include "chap08/test_counting_sort.h"
 #include "chap08/test_radix_sort.h"
+#include "chap09/test_order_statistic.h"
 #include "chap15/test_optimal_binary_search_tree.h"
 #include "utils.h"
 #include <stdio.h>
@@ -33,6 +34,7 @@ int main() {
     CHECK_CU_RETURN(add_test_quick_sort());
     CHECK_CU_RETURN(add_test_counting_sort());
     CHECK_CU_RETURN(add_test_radix_sort());
+    CHECK_CU_RETURN(add_test_order_statistic());
     CHECK_CU_RETURN(add_test_obst());
 
     //使用console控制交互界面的函数入口

utils.c

@@ -4,6 +4,7 @@
  */
 #include "utils.h"
 #include <stdio.h>
+#include <stdlib.h>
 #include <math.h>
 
 void print_array(int nums[], int len) {
@@ -72,3 +73,10 @@ int get_dgt_cnt(int num) {
     return i;
 }
 
+void shuffle(int nums[], int len) {
+    // 最后一个位置自动确定了
+    for (int i = len-1; i > 0; i--) {
+        swap(nums, i, rand()%(i+1));
+    }   
+}
+

utils.h

@@ -29,4 +29,5 @@ int maxnum(int a, int b);
 int minnum(int a, int b);
 int get_ith_dgt(int num, int i);
 int get_dgt_cnt(int num);
+void shuffle(int nums[], int len);
 #endif