TA release HW1

1/exp2/binary_insert_sort.cpp

@@ -0,0 +1,58 @@
+#include "stdio.h"
+/*
+  二分插入排序：通过二分查找找到插入位置，然后将元素插入到指定位置。
+*/
+
+// 统计待排序数据的比较次数
+int compare_count = 0;
+
+// 递归二分查找插入位置
+int binary_search(int v[], int left, int right, int n)
+{
+    if (left > right)
+        return left; // 递归边界，此处不统计比较次数
+    int mid = (left + right) >> 1;
+    compare_count++; // 统计比较次数
+    if (v[mid] > v[n])
+        return binary_search(v, left, mid - 1, n);
+    else
+        return binary_search(v, mid + 1, right, n);
+}
+
+// 将新的元素插入到指定位置，并将后续元素后移
+void insert(int *v, int k, int n)
+{
+    int i;
+    int tmp = v[n];
+    for (i = n - 1; i >= k; i--)
+    {
+        v[i + 1] = v[i];
+    }
+    v[k] = tmp;
+}
+
+void binary_insertion_sort(int v[], int n)
+{
+    int i;
+    for (i = 1; i < n; i++)
+    { // 从第二个元素开始，依次插入到前面已经排好序的序列中
+        int place = binary_search(v, 0, i - 1, i);
+        insert(v, place, i);
+    }
+}
+
+int main()
+{
+    FILE *infile, *outfile;
+    int buffer[1001];
+    infile = fopen("a.in", "rb");
+    fread(buffer, 4, 1001, infile);
+    fclose(infile);
+    int N = buffer[0];
+    binary_insertion_sort(&(buffer[1]), N);
+    buffer[0] = compare_count;
+    outfile = fopen("a.out", "wb");
+    fwrite(buffer, 4, N + 1, outfile);
+    fclose(outfile);
+    return 0;
+}