hi, This crashes on g++ 4.2.3. I think my code is correct. I'm not doing any out of bound errors but sort crashes. Same is present at http://rafb.net/p/nyMKCk70.html or http://pastebin.com/m67e4529b Why does this occur ? unk@edubuntu:~/prog/mipt$ gdb ./a.out GNU gdb 6.8-debian Copyright (C) 2008 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "i486-linux-gnu"... (gdb) run < inh Starting program: /home/junk/prog/mipt/a.out < inh Program received signal SIGSEGV, Segmentation fault. 0x08048beb in std::__unguarded_partition<int*, int, bool (*)(int, int)> (__first=0x8363000, __last=0x8361d70, __pivot=18, __comp=0x8048634 <cmp(int, int)>) at /usr/include/c++/4.2/bits/stl_algo.h:2278 2278 while (__comp(*__first, __pivot)) (gdb) ===========source code================= #include<cstdio> #include<algorithm> #include<iostream> using namespace std; #define MAX 900 char str[MAX]; int graph[MAX][MAX], n, arr[MAX]; bool cmp (const int a, const int b) { if (a > 0 && a <= n && b > 0 && b <= n) { if (graph[a][b] == 1) return true; if (graph[a][b] == -1) return false; } return true; } int main () { int k = 1, i, z, j, st = -1; scanf (" %d", &n); for (i = 1; i <= n; i++) arr[i] = i; for (z = 0; z < n; z++) { scanf (" %s", str); for (i = 0; i<k && str[i] && (str[i] != '#'); i++) { if (str[i] == '+') { graph[k][i + 1] = 1; graph[i + 1][k] = -1; } else if (str[i] == '-') { graph[k][i + 1] = -1; graph[i + 1][k] = 1; } } sort (arr + 1, arr + n + 1, cmp); k++; } for (i = 1; i < n; i++) printf ("%d ", arr[i]); printf ("%d\n", arr[i]); return 0; } ========input======================= 35 # +# ++# +++# ++++# +++++# ++++++# +++++++# ++++++++# +++++++++# ++++++++++# +++++++++++# ++++++++++++# +++++++++++++# ++++++++++++++# +++++++++++++++# ++++++++++++++++# +++++++++++++++++# ++++++++++++++++++# +++++++++++++++++++# ++++++++++++++++++++# +++++++++++++++++++++# ++++++++++++++++++++++# +++++++++++++++++++++++# ++++++++++++++++++++++++# +++++++++++++++++++++++++# ++++++++++++++++++++++++++# +++++++++++++++++++++++++++# ++++++++++++++++++++++++++++# +++++++++++++++++++++++++++++# ++++++++++++++++++++++++++++++# +++++++++++++++++++++++++++++++# ++++++++++++++++++++++++++++++++# +++++++++++++++++++++++++++++++++# ++++++++++++++++++++++++++++++++++#
