Minimum K count, K count

Minimum K count, K count
Question: Enter n Integers to find the minimum K number. For example, if you enter the 8 numbers, the minimum four digits are, and ,.

Train of Thought 1: We can find the k number through the fast sorting, and all the smaller ones than him are on the left, and the bigger ones are on the right.

Idea 2: to deal with big data, first take the first k digits in the array to create a large root heap. After the heap is established, start from the k + 1 element and compare it with the heap top element, if it is smaller than the heap top element, it replaces the heap top element.

1 # include "stdafx. h "2 # include <iostream> 3 # include <set> 4 # include <vector> 5 # include <stdlib. h> 6 # include <tchar. h> 7 # include <exception> 8 using namespace std; 9 10 int RandomInRange (int min, int max) 11 {12 int random = rand () % (max-min + 1) + min; 13 return random; 14} 15 16 void Swap (int * num1, int * num2) 17 {18 int temp = * num1; 19 * num1 = * num2; 20 * num2 = temp; 21} 22 23 int Partit Ion (int data [], int length, int start, int end) 24 {25 if (data = NULL | length <= 0 | start <0 | end> = length) 26 // throw std :: exception ("Invalid Parameters"); 27 exit (1); 28 29 int index = RandomInRange (start, end); 30 Swap (& data [index], & data [end]); 31 32 int small = start-1; 33 for (index = start; index <end; ++ index) 34 {35 if (data [index] <data [end]) 36 {37 ++ small; 38 if (small! = Index) 39 Swap (& data [index], & data [small]); 40} 41} 42 43 + + small; 44 Swap (& data [small], & data [end]); 45 46 return small; 47} 48 49 // ================================ method 1 ================ ============ 50 void GetLeastNumbers_Solution1 (int * input, int n, int * output, int k) 51 {52 if (input = NULL | output = NULL | k> n | n <= 0 | k <= 0) 53 return; 54 55 int start = 0; 56 int end = n-1; 57 int index = P Artition (input, n, start, end); 58 while (index! = K-1) 59 {60 if (index> k-1) 61 {62 end = index-1; 63 index = Partition (input, n, start, end ); 64} 65 else 66 {67 start = index + 1; 68 index = Partition (input, n, start, end); 69} 70} 71 72 for (int I = 0; I <k; ++ I) 73 output [I] = input [I]; 74} 75 76 // ================================= method 2 ====================== ============ 77 typedef multiset <int, greater <int> intSet; 78 typedef multiset <int, greater <int> >:: Iterator setIterator; 79 80 void GetLeastNumbers_Solution2 (const vector <int> & data, intSet & leastNumbers, int k) 81 {82 leastNumbers. clear (); 83 84 if (k <1 | data. size () <k) 85 return; 86 87 vector <int>: const_iterator iter = data. begin (); 88 for (; iter! = Data. end (); ++ iter) 89 {90 if (leastNumbers. size () <k) 91 leastNumbers. insert (* iter); 92 93 else 94 {95 setIterator iterGreatest = leastNumbers. begin (); 96 97 if (* iter <* (leastNumbers. begin () 98 {99 leastNumbers. erase (iterGreatest); 100 leastNumbers. insert (* iter); 101} 102} 103} 104} 105 106 int main () 107 {108 109 int data [] = {4, 5, 1, 6, 2, 7, 3, 8}; 110 int length = sizeof (data)/sizeof (Int); 111 int k = 4; 112 113 printf ("The data is: \ n"); 114 for (int I = 0; I <length; ++ I) 115 printf ("% d \ t", data [I]); 116 printf ("\ n"); 117 118 vector <int> vectorData; 119 for (int I = 0; I <length; ++ I) 120 vectorData. push_back (data [I]); 121 122 printf ("Result for solution1: \ n"); 123 124 int * output = new int [k]; 125 GetLeastNumbers_Solution1 (data, length, output, k); 126 127 for (int I = 0; I <k; + + I) 128 printf ("% d \ t", output [I]); 129 printf ("\ n"); 130 131 delete [] output; 132 133 printf ("Result for solution2: \ n"); 134 135 intSet leastNumbers; 136 GetLeastNumbers_Solution2 (vectorData, leastNumbers, k); 137 138 printf ("The actual output numbers are: \ n "); 139 140 for (setIterator iter = leastNumbers. begin (); iter! = LeastNumbers. end (); ++ iter) 141 printf ("% d \ t", * iter); 142 printf ("\ n"); 143 144 145 return 0; 146}