数字在排序数组中出现的次数

来源：互联网发布：余弦相似度公式 python 编辑：程序博客网时间：2024/06/11 17:53

题目描述

统计一个数字在排序数组中出现的次数。

#include <iostream>using namespace std;int GetFirstOfK(int* arr,int k, int start, int end){if(start > end)return -1;int MiddIndex = (start + end) / 2;int Middata = arr[MiddIndex];if(Middata == k){if((Middata > 0 && arr[MiddIndex -1] != k) || MiddIndex == 0)return MiddIndex;elseend = MiddIndex -1;}else if(Middata > k){end = MiddIndex - 1;}else{start = MiddIndex + 1;}return GetFirstOfK(arr, k, start, end);}int GetLastOfK(int *arr, int k, int start, int end ,int length){if(start > end)return -1;int MiddIndex = (start + end) / 2;int Middata = arr[MiddIndex];if(Middata == k){if((MiddIndex < length-1 && arr[MiddIndex + 1] != k) || MiddIndex == length - 1)return MiddIndex;elsestart = MiddIndex + 1;}else if(Middata > k){end = MiddIndex - 1;}else{start = MiddIndex + 1;}return GetLastOfK(arr, k, start, end, length);}int GetNumberOfK(int *arr, int length, int k){if(arr == NULL || length <= 0)return 0;int number = 0;int begin = GetFirstOfK(arr, k, 0, length - 1);int end = GetLastOfK(arr, k, 0, length - 1, length);if(begin > -1 && end > -1)number = end - begin + 1;return number;}

// ====================测试代码====================void Test(char* testName, int data[], int length, int k, int expected){    if(testName != NULL)        printf("%s begins: ", testName);    int result = GetNumberOfK(data, length, k);    if(result == expected)        printf("Passed.\n");    else{        printf("Failed.\n");printf("%d\n",result);}}// 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", NULL, 0, 0, 0);}int main(int argc, char* argv[]){    Test1();    Test2();    Test3();    Test4();    Test5();    Test6();    Test7();    Test8();    Test9();    Test10();    Test11();    return 0;}

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