几种面试常见的算法(C++实现)

#include <iostream>
using namespace std;

void quickSort(int s[], int left, int right) //快速排序
{
    if (left < right) {
        int i = left, j = right, x = s[left];
        while (i < j) {
            while (i < j && s[j] >= x) {
                j--;
            }

            if (i < j) {
                s[i++] = s[j];
            }

            while (i < j && s[i] < x) {
                i++;
            }

            if (i < j) {
                s[j--] = s[i];
            }
        }
        s[i] = x;
        quickSort(s, left, i -1);
        quickSort(s, i + 1, right);
    }
}

int binarySearch(int arr[], int length, int flied) //二分查找
{
    int low = 0, high = length, middle = 0;
    while (low < high) {
        middle = (low + high) / 2;
        if (flied == arr[middle]) {
            return middle;
        } else if(flied < arr[middle]) {
            high = middle;
        } else if (flied > arr[middle]) {
            low = middle + 1;
        }
    }
    return -1;
}

void bubbleSort(int arr[], int length)  //冒泡排序
{
    int i, j;
    for (i = 0; i < length - 1; i++) {
        for (j = 0; j < length - 1; j++) {
            if (arr[j] < arr[j + 1]) {
                swap(arr[j], arr[j + 1]);
            }
        }
    }
}

void insertSort(int a[],int len){  //插入排序
    for(int i=1;i<len;i++){
        int tmp=a[i];
        int j=i-1;
        while(j>=0 && tmp<a[j]){
            a[j+1]=a[j];
            j--;
        }
        a[j+1]=tmp;
    }
}

void selectSort(int a[],int len){  //选择排序
    for(int i=0;i<len-1;i++){
        int minidx=i;
        for(int j=i+1;j<len;j++){
            if(a[j]<a[minidx]){
                minidx=j;
            }
        }
        if(a[i]>a[minidx]){
            int tmp=a[i];
            a[i]=a[minidx];
            a[minidx]=tmp;
        }
    }
}

void shellsort(int a[],int len){  //希尔排序
    //划分成gap个组
    for(int gap=len/2;gap>0;gap/=2){
        //从第gap个元素，逐个对其所在组进行插入排序操作
        //而不需要for每个组进行操作
        for(int i=gap;i<len;i++){
            int j=i-gap;
            //插入排序采用交换法即可
            while(j>=0 && a[j]>a[j+gap]){
                swap(a[j],a[j+gap]);
                j-=gap;
            }
        }
    }
}

int main()
{
    int array[] = {21, 3, 43, 53, 323, 32, 321, 9, 0, 2, 3232, 4, 1}, k;
    int len = sizeof(array) / sizeof(int);
    cout<<"The orginal arrayare is:"<<endl;
    for(k=0;k<len;k++) {
        cout<<array[k]<<",";
    }
    cout<<endl;
    bubbleSort(array, len);
    //shellsort(array, len);
    selectSort(array, len);
    //insertSort(array, len);
    //quickSort(array,0,len - 1);
    cout<<"The sorted arrayare is:"<<endl;
    for(k=0;k<len;k++) {
        cout<<array[k]<<",";
    }
    cout<<endl;

    cout<<"===============================Binary Search:"<< endl;

    int arr2[] = {1, 2, 3, 4, 5, 6, 7, 77, 200, 500}, i;
    int length = sizeof(arr2) / sizeof(int);
    int filed = 200;
    int place = binarySearch(arr2, length, filed);
    cout << "arrar is : ";
    for(i = 0; i < length; i++) {
        cout<< arr2[i] <<",";
    }
    cout<<"\n";
    cout << "length is : " << length <<endl;
    cout << "filed is : " << filed <<endl;
    cout << "place is : " << place <<endl;

    system("pause");  //暂停一下   请按任意键继续...........
    return 0;
}