static void resort(char[] s) { int n = s.length; int[] f = new int[n]; int count = 0; for (int i=n-1; i>=0; i--) { if (s[i] != '#') { f[i] = count; } else { count ++; } } for (int i=n-1; i>=0; i--) { if (s[i] != '#') { s[i+f[i]] = s[i]; } } for (int i=0; i<count; i++) { s[i] = '#'; } }