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: [email protected]
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("\n");
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\n", ret);
115
116 return 0;
117 }