Select the top 10 [C Language] From N

Question: select the top 10 largest N numbers for ordered output. N is up to 100 billion. The value range is 0-2147483647: input 1 million entries total [1000000] total input comparison [2001654] Total write memory [552] total time consumption [0.014687 s] C language version solution [cpp] # include <stdio. h> # include <time. h> # include <stdlib. h> # include <unistd. h> # include <strings. h>/** author: goosman. lei * mail: lgg860911@yahoo.com.cn * blog: http://blog.csdn.net/lgg201 */# Define BUFF_LEN (4096)/* # define DEBUG */# define INFO typedef struct queue_s queue_t; struct queue_s {int data; queue_t * next ;}; static void generate_test_data (long n) {long I; int r; int l; l = sizeof (int); srand (time (NULL); for (I = 0; I <n; I ++) {r = rand (); fprintf (stdout, "% d \ n", r); write (STDERR_FILENO, & r, l) ;}} static int read_input (int fd, void * buff, int buff_len) {int I, Ret; for (I = 0; I <buff_len;) {ret = read (fd, buff, BUFF_LEN); if (-1 = ret) {perror ("read error \ n"); exit (0);} else if (0 = ret) {break;} else {buff + = ret; I + = ret ;}} return I;} static void dump_link (queue_t * q, int n) {for (; q! = NULL; q = q-> next) fprintf (n? Stderr: stdout, "% d \ n", q-> data); if (n) printf ("\ n");} int main (int argc, char * argv []) {int * sbuff; int I, j, n; queue_t * rbuff, ** tmp, * t; # ifdef INFO int s_0, s_1, s_2; struct timeval begin, end; # endif if (argc <2) {printf ("usage: \ n \ t1. Generate Test Data: % s <number>/* The standard error outputs the test data in binary mode, and the standard output outputs the test data in text mode for script verification */\ n \ t2. execute the Top 10 search: % s <exec>/* maximum data (in descending order) before standard output. When INFO is enabled, statistics are output in standard errors. When DEBUG is enabled Error output debugging information \ n ", argv [0], argv [0]); return (0);} if (strcmp (argv [1]," exec ")! = 0) {/* digit input error tolerance */generate_test_data (atoi (argv [1]); return 0 ;} sbuff = malloc (1024*1024*4); rbuff = malloc (sizeof (queue_t) * 10);/* buffer initialization */bzero (rbuff, sizeof (queue_t) * 10); for (I = 0; I <9; I ++) {(rbuff + I)-> next = (rbuff + I + 1 ); (rbuff + I)-> data =-1;} (rbuff + 9)-> data =-1; (rbuff + 9)-> next = NULL; # ifdef DEBUG dump_link (rbuff, 1); # endif # ifdef INFO s_0 = 0; s_1 = 0; s_2 = 0; gettimeofday (& begin, NULL); # endif while (0! = (N = read_input (STDIN_FILENO, sbuff, 1024*1024*4) {# ifdef INFO s_0 ++; # endif j = n/4; # ifdef INFO s_2 + = j; # endif for (I = 0; I <j; I ++) {# ifdef INFO s_0 ++; # endif # ifdef DEBUG fprintf (stderr, "processing % d \ n", * (sbuff + I); # endif for (tmp = & rbuff; * tmp! = NULL & * (sbuff + I)> = (* tmp)-> data;) {tmp = & (* tmp)-> next ); # ifdef INFO s_0 + = 2; # endif} # ifdef INFO s_0 ++; # endif if (* tmp = rbuff) {continue;} # ifdef DEBUG fprintf (stderr, "tmp % d % p, rbuff % d % p \ n", (* tmp) = NULL? -1: (* tmp)-> data, * tmp, rbuff-> data, rbuff); # endif rbuff-> data = * (sbuff + I ); # ifdef INFO s_1 ++; s_0 ++; # endif if (* tmp! = Rbuff-> next) {t = rbuff; rbuff = rbuff-> next; t-> next = NULL = * tmp? NULL: * tmp; * tmp = t; # ifdef INFO s_1 + = 4; s_0 ++; # endif} # ifdef DEBUG dump_link (rbuff, 1 ); # endif }# ifdef INFO gettimeofday (& end, NULL); # endif dump_link (rbuff, 0); # ifdef INFO fprintf (stderr, "Total [% d] input \ n total comparison [% d] times \ n total write memory [% d] times \ n total time consumed [% 0.6fs] \ n ", s_2, s_0, s_1, (end. TV _sec * 1000000 + end. TV _usec-begin. TV _sec * 1000000-begin. TV _usec)/1000000.0); # endif return 0 ;}