最小的K个数（面试题 30）

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题目：输入n个整数，找出其中最小的k个数。例如输入4,5,1,6,2,7,3,8这8个数字，则最小的4个数字是1,2,3,4。

#include "iostream"using namespace std;int partition(int array[],int low,int high){int pivot =array[low];while(low<high){while(low<high&&array[high]>=pivot) high--;array[low] =array[high];while(low<high&&array[low]<=pivot)low++;array[high] =array[low];}array[low] =pivot;return low;}//利用二分的思想，但是会修改数组内容void GetLeastNumbers(int* input,int n,int* output,int k){if(input ==NULL ||output ==NULL||k>n||n<=0||k<=0)return;int start =0;int end =n-1;int index =partition(input,start,end);while(index !=k-1){if (index>k-1){end =index -1;index =partition(input,start,end);}else{start =index +1;index =partition(input,start,end);}}for (int i=0;i<k;i++){output[i] =input[i];}}void main(){int array[8] ={3,5,1,6,2,7,0,8};int output[10];GetLeastNumbers(array,8,output,4);for (int i=0;i<4;i++){cout<<output[i]<<"  ";}cout<<endl;}

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