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DSBookCode/BookCode/第7章/7.3.cpp

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+//算法7.3　折半查找
+
+
+
+#include<iostream>
+using namespace std;
+#define MAXSIZE 100
+#define OK 1;
+
+typedef struct{
+	int key;//关键字域
+}ElemType;
+
+typedef struct{
+	ElemType *R;
+	int length;
+}SSTable;
+
+int InitList_SSTable(SSTable &L)
+{
+	L.R=new ElemType[MAXSIZE];
+	if (!L.R)
+	{
+		cout<<"初始化错误";
+		return 0;
+	}
+	L.length=0;
+	return OK;
+}
+
+int Insert_SSTable(SSTable &L) 
+{
+	int j=1;
+	for(int i=1;i<MAXSIZE;i++)
+	{
+		L.R[i].key=j;
+		L.length++;
+		j++;
+	}
+	return 1;
+}
+
+int Search_Bin(SSTable ST,int key) {
+   // 在有序表ST中折半查找其关键字等于key的数据元素。若找到，则函数值为
+   // 该元素在表中的位置，否则为0
+   int low=1,high=ST.length;							//置查找区间初值
+   int  mid;
+   while(low<=high) {
+	   mid=(low+high) / 2;
+      if (key==ST.R[mid].key)  return mid;      		//找到待查元素
+      else if (key<ST.R[mid].key)  high = mid -1;		//继续在前一子表进行查找
+      else  low =mid +1;                       			//继续在后一子表进行查找
+   }//while
+   return 0;										//表中不存在待查元素
+}// Search_Bin
+
+void Show_End(int result,int testkey)
+{
+	if(result==0)
+		cout<<"未找到"<<testkey<<endl;
+	else
+		cout<<"找到"<<testkey<<"位置为"<<result<<endl;
+	return;
+}
+
+void main()
+{
+	SSTable ST;
+	InitList_SSTable(ST);
+	Insert_SSTable(ST);
+	int testkey1=7,testkey2=200;
+	int result;
+	result=Search_Bin(ST, testkey1);
+	Show_End(result,testkey1);
+	result=Search_Bin(ST, testkey2);
+	Show_End(result,testkey2);
+}