剑指offer--面试题53 在排序数组中查找数字（二分）

来源：互联网发布：上海美猴网络骗局编辑：程序博客网时间：2024/06/16 10:59
//数字在排序数组中出现的次数#include <iostream>using namespace std;int GetFirstK(const int* data,int length,int k,int start,int end);int GetLastK(const int* data,int length,int k,int start,int end);int GetNumberOfK(int* data,int length,int k){    int number = 0;    if(data!=nullptr&&length>0)    {        int first = GetFirstK(data,length,k,0,length-1);        int last = GetLastK(data,length,k,0,length-1);        if(last>-1&&first>-1)            number =last - first+1;    }    return number;}int GetFirstK(const int* data,int length,int k,int start,int end){    if(start>end)        return -1;    int middleIndex = (start+end)/2;    int middleData = data[middleIndex];    if(middleData==k)    {        if((middleIndex>0&&data[middleIndex-1]!=k)||middleIndex==0)            return middleIndex;        else            end = middleIndex-1;    }    else if(middleData>k)    {        end = middleIndex-1;    }    else    {        start = middleIndex+1;    }    return GetFirstK(data,length,k,start,end);}int GetLastK(const int* data,int length,int k,int start,int end){    if(start>end)        return -1;    int middleIndex = (start+end)/2;    int middleData = data[middleIndex];    if(middleData==k)    {        if((middleIndex<length-1 && data[middleIndex+1]!=k)||middleIndex ==length-1)            return middleIndex;        else            start = middleIndex+1;    }    else if(middleData>k)    {        end = middleIndex-1;    }    else    {        start = middleIndex+1;    }    return GetLastK(data,length,k,start,end);}// ====================测试代码====================void Test(const char* testName, int data[], int length, int k, int expected){    if(testName != nullptr)        printf("%s begins: ", testName);    int result = GetNumberOfK(data, length, k);    if(result == expected)        printf("Passed.\n");    else        printf("Failed.\n");}// 查找的数字出现在数组的中间void Test1(){    int data[] = {1, 2, 3, 3, 3, 3, 4, 5};    Test("Test1", data, sizeof(data) / sizeof(int), 3, 4);}// 查找的数组出现在数组的开头void Test2(){    int data[] = {3, 3, 3, 3, 4, 5};    Test("Test2", data, sizeof(data) / sizeof(int), 3, 4);}// 查找的数组出现在数组的结尾void Test3(){    int data[] = {1, 2, 3, 3, 3, 3};    Test("Test3", data, sizeof(data) / sizeof(int), 3, 4);}// 查找的数字不存在void Test4(){    int data[] = {1, 3, 3, 3, 3, 4, 5};    Test("Test4", data, sizeof(data) / sizeof(int), 2, 0);}// 查找的数字比第一个数字还小，不存在void Test5(){    int data[] = {1, 3, 3, 3, 3, 4, 5};    Test("Test5", data, sizeof(data) / sizeof(int), 0, 0);}// 查找的数字比最后一个数字还大，不存在void Test6(){    int data[] = {1, 3, 3, 3, 3, 4, 5};    Test("Test6", data, sizeof(data) / sizeof(int), 6, 0);}// 数组中的数字从头到尾都是查找的数字void Test7(){    int data[] = {3, 3, 3, 3};    Test("Test7", data, sizeof(data) / sizeof(int), 3, 4);}// 数组中的数字从头到尾只有一个重复的数字，不是查找的数字void Test8(){    int data[] = {3, 3, 3, 3};    Test("Test8", data, sizeof(data) / sizeof(int), 4, 0);}// 数组中只有一个数字，是查找的数字void Test9(){    int data[] = {3};    Test("Test9", data, sizeof(data) / sizeof(int), 3, 1);}// 数组中只有一个数字，不是查找的数字void Test10(){    int data[] = {3};    Test("Test10", data, sizeof(data) / sizeof(int), 4, 0);}// 鲁棒性测试，数组空指针void Test11(){    Test("Test11", nullptr, 0, 0, 0);}int main(int argc, char* argv[]){    Test1();    Test2();    Test3();    Test4();    Test5();    Test6();    Test7();    Test8();    Test9();    Test10();    Test11();    return 0;}
数字在排序数组中出现的次数
0 0