title: valgrind : what does the following summary tells
body: <p>First have a look at my code .It is giving runtime error(sigsegv) on an online judge, though works perfetly fine on my computer.Please help me find out the error.</p>
  
  <p>The constraints are:</p>
  
  <p>0&lt; t1 &lt;1000000</p>
  
  <p>0&lt; num &lt;100000000</p>
  
  <pre><code>#include&lt;stdio.h&gt;
  
  #include&lt;malloc.h&gt;
  
  int *a;
  
  int main()
  
  {
  
     a = malloc(sizeof(int)*100000000);
  
  
  
     int  t=3,j,k1,k=1,n=0,i,t1,num;
  
  
  
     for(i=1;i&lt;10000;i++)
  
        {
  
                    // m=i*i;
  
                     n=n+t;
  
                     for(j=i*i;j&lt;=n;j++)
  
  
  
                                      a[j]=k;
  
  
  
                     k++;
  
                     t=t+2;
  
  
  
       }
  
    scanf("%d",&amp;t1);
  
  
  
     for(k1=0;k1&lt;t1;k1++)
  
     {
  
          scanf("%d",&amp;num);
  
          printf("%d\n",a[num]);
  
     }
  
    free(a);
  
    //getch();
  
     return 0;
  
  }
  </code></pre>
  
  <p>I ran this simple code  using valgrind. It gave the following output,i am newbie to valgrind so please tell me what does it mean.</p>
  
  <pre><code>singu@singu-Studio-1450 ~ $ valgrind --leak-check=yes ./doors
  ==4732== Memcheck, a memory error detector
  ==4732== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
  ==4732== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info
  ==4732== Command: ./doors
  ==4732== 
  ==4732== Warning: set address range perms: large range [0x51c3040, 0x1cf3b440)     (undefined)
  ==4732== Invalid write of size 4
  ==4732==    at 0x400662: main (doors.c:16)
  ==4732==  Address 0x1cf3b440 is 0 bytes after a block of size 400,000,000 alloc'd
  ==4732==    at 0x4C28FAC: malloc (vg_replace_malloc.c:236)
  ==4732==    by 0x400605: main (doors.c:6)
  ==4732== 
  ^C==4732== 
  ==4732== HEAP SUMMARY:
  ==4732==     in use at exit: 400,000,000 bytes in 1 blocks
  ==4732==   total heap usage: 1 allocs, 0 frees, 400,000,000 bytes allocated
  ==4732== 
  ==4732== LEAK SUMMARY:
  ==4732==    definitely lost: 0 bytes in 0 blocks
  ==4732==    indirectly lost: 0 bytes in 0 blocks
  ==4732==      possibly lost: 0 bytes in 0 blocks
  ==4732==    still reachable: 400,000,000 bytes in 1 blocks
  ==4732==         suppressed: 0 bytes in 0 blocks
  ==4732== Reachable blocks (those to which a pointer was found) are not shown.
  ==4732== To see them, rerun with: --leak-check=full --show-reachable=yes
  ==4732== 
  ==4732== For counts of detected and suppressed errors, rerun with: -v
  ==4732== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 4 from 4)
  </code></pre>