H-Index
Given an array of citations (each citation is a non-negative integer)
of a researcher, write a function to compute the researcher's h-index.
According to the definition of h-index on Wikipedia:
"A scientist has index h if h of his/her N papers have
at least h citations each, and the other N ? h papers have
no more than h citations each."
For example, given citations = [3, 0, 6, 1, 5],
which means the researcher has 5 papers in total and each of them
had received 3, 0, 6, 1, 5 citations respectively.
Since the researcher has 3 papers with at least 3 citations each
and the remaining two with no more than 3 citations each,
his h-index is 3.
Note:
If there are several possible values for h,
the maximum one is taken as the h-index.
Hint:
An easy approach is to sort the array first.
What are the possible values of h-index?
A faster approach is to use extra space.
1 /************************************************************************* 2 > File Name: LeetCode274.c 3 > Author: Juntaran 4 > Mail: JuntaranMail@gmail.com 5 > Created Time: Thu 19 May 2016 20:47:36 PM CST 6 ************************************************************************/ 7 8 /************************************************************************* 9 10 H-Index 11 12 Given an array of citations (each citation is a non-negative integer) 13 of a researcher, write a function to compute the researcher's h-index. 14 15 According to the definition of h-index on Wikipedia: 16 "A scientist has index h if h of his/her N papers have 17 at least h citations each, and the other N ? h papers have 18 no more than h citations each." 19 20 For example, given citations = [3, 0, 6, 1, 5], 21 which means the researcher has 5 papers in total and each of them 22 had received 3, 0, 6, 1, 5 citations respectively. 23 Since the researcher has 3 papers with at least 3 citations each 24 and the remaining two with no more than 3 citations each, 25 his h-index is 3. 26 27 Note: 28 29 If there are several possible values for h, 30 the maximum one is taken as the h-index. 31 32 Hint: 33 34 An easy approach is to sort the array first. 35 What are the possible values of h-index? 36 A faster approach is to use extra space. 37 38 ************************************************************************/ 39 40 #include "stdio.h" 41 42 void quick_sort( int* nums, int left, int right ) 43 { 44 if( left < right ) 45 { 46 int i = left; 47 int j = right; 48 int flag = nums[left]; 49 50 while( i < j ) 51 { 52 while( i<j && nums[j]>=flag ) // 从右向左找第一个小于x的数 53 { 54 j--; 55 } 56 if( i < j ) 57 { 58 nums[i++] = nums[j]; 59 } 60 61 while( i<j && nums[i]<flag ) // 从左向右找第一个大于等于x的数 62 { 63 i++; 64 } 65 if( i < j ) 66 { 67 nums[j--] = nums[i]; 68 } 69 } 70 nums[i] = flag; 71 quick_sort( nums, left, i-1 ); 72 quick_sort( nums, i+1, right); 73 } 74 } 75 76 void printfNums( int* nums, int numsSize ) 77 { 78 int i; 79 for( i=0; i<numsSize; i++ ) 80 { 81 printf("%d ", nums[i]); 82 } 83 printf(" "); 84 } 85 86 int hIndex(int* citations, int citationsSize) 87 { 88 89 quick_sort( citations, 0, citationsSize-1 ); 90 91 int i; 92 for( i=0; i<citationsSize; i++ ) 93 { 94 if( (citationsSize-i) <= citations[i] ) 95 { 96 return citationsSize-i; 97 } 98 } 99 return 0; 100 } 101 102 int main() 103 { 104 int citations[] = {9,8,7,6,5,4,3,2,1}; 105 int citationsSize = 9; 106 int left = 0; 107 int right = 8; 108 109 printfNums( citations, citationsSize ); 110 quick_sort( citations, left, right ); 111 printfNums( citations, citationsSize ); 112 113 int ret = hIndex( citations, citationsSize ); 114 printf("%d ", ret); 115 116 return 0; 117 }