Algorithm Competition Introduction Classic example 3-1 turn on the light problem

There are n lights, numbered 1~n, the 1th person to turn all the lights on, the 2nd person presses all the switches numbered in multiples of 2 (these lights will be turned off), the 3rd person presses all the switches numbered in multiples of 3 (where the lights are turned on, the lights are turned off), and so on. A total of k individuals, asked the last which lights on?

Input: N and K, the output light number of the open. k≤n≤1000.

Sample Input: 7 3

Sample output: 1 5 6 7

#include <stdio.h> #include <stdlib.h> #include <string.h> #define MAXN 10int A[maxn];int Main ( int argc, char *argv[]) {  int i, J, N, K, first = 1;  scanf ("%d%d", &n, &k);  Memset (A,-1, sizeof (a));  for (i = 1; l <= K; i++) for     (j = 1; J <= N; j + +)     {        if (j%i = = 0) A[j] =-a[j];     }     /*   for (j = 1; J <= N; j + +)     if (a[j] = = 1) printf ("%d", j); Finally there should be no space */For                                   (j = 1; J <= N; + j)     if (a[j] = 1) {if (first) first = 0; else printf (""); printf ("%d", j);}  printf ("\ n");     Finally, the output line break   system ("PAUSE");  return 0;}

Summary: 1 Use a flag to determine whether the first output, if, do not output space, or lose the first space after the loss of digital

2 switching lights can also be used 0 1

Algorithm Contest Introduction Classic example 3-1 open light problem