寻找最大值与最小值
概述
本文将给出寻找最大值和最小值的常规方法与改进方法，采用改进算法明显降低了比较次数，性能更优。
代码
#include <iostream>
using namespace std;
/**
* It is used to get the maximum and minmum by using the common method.
* @arr store the array value
* @length store the array length
* @author Junpeng Zhu
*/
int* commonMethod(int* arr, int length){
int max = arr[0];
int min = arr[0];
for (int i = 1; i < length; i++){
if(max < arr[i]){
max = arr[i];
}
if(min > arr[i]){
min = arr[i];
}
}
int* results = new int[2];
results[0]= min;
results[1] = max;
return results;
}
/**
* It is used to get the maximum and minmum by using the enhancing method.
* The number of comparsion decreases by comparing to the common method.
* @arr store the array value
* @length store the array length
* @author Junpeng Zhu
*/
int* enhancingMethod(int arr[], int length){
if(length % 2 == 0){
int max = arr[0]>arr[1]?arr[0]:arr[1];
int min = arr[0]<arr[1]?arr[0]:arr[1];
for (int i = 2; i<length;){
if(arr[i] > arr[i+1]){
if(arr[i] > max){
max = arr[i];
}
if(arr[i+1] < min){
min = arr[i+1];
}
i += 2;
}else{
if(arr[i+1] > max){
max = arr[i+1];
}
if(arr[i]<min){
min = arr[i];
}
i += 2;
}
}
int* results = new int[2];
results[0] = min;
results[1] = max;
return results;
}else{
int max = arr[0];
int min = arr[0];
for (int i = 1; i < length ;){
if(arr[i] > arr[i+1]){
if(arr[i] > max){
max = arr[i];
}
if(arr[i+1] < min){
min = arr[i+1];
}
i += 2;
}else{
if(arr[i+1] > max){
max = arr[i+1];
}
if(arr[i]<min){
min = arr[i];
}
i += 2;
}
}
int* results = new int[2];
results[0] = min;
results[1] = max;
return results;
}
}
int main()
{
//int arr[] = {3,2,1}; //success
//int arr[] = {2,8,7,1,3,5,6,4}; //success
//int arr[] = {3,5,4,6,2,1}; //success
//int arr[] = {3,5,4,6,2,1}; //success
//int arr[] = {2,5,2,4,1,1}; //success
int arr[] = {13,19,9,5,12,8,7,4,11,2,6,21}; //success
//int arr[] = {8,10,7,16,10,3,9,7,20,2}; //success
//int arr[] = {8,10,7,16,8,3,9,7,20,2}; //success, compare to the above example {8,10,7,16,10,3,9,7,20,2}
//int arr[] = {1,1,3}; //success
//int arr[] = {1,1,1,1,1,1,1}; //success
int length = sizeof(arr)/sizeof(arr[0]);
//int* results = commonMethod(arr,length);
int* results = enhancingMethod(arr,length);
int resultsLength = sizeof(results)/sizeof(results[0]);
//cout << sizeof(results)/sizeof(results[0]) << endl;
for(int i = 0; i < resultsLength;i++){
cout << results[i] << " ";
}
return 0;
}