# simple bst problem

my code is giving wa for following test case.
it never prints hello i.e.never enters the condition prev->val>A->val
i have no clue why?
is there any fault in my approach?
Also,can we do this question in constant space?
code:

vector vec;

void iit(TreeNode* A,TreeNode* prev)
{
if(A==NULL)return;
iit(A->left,prev);
if(prev!=NULL)
{ // cout<<“jkl”;
if(prev->val>A->val)
{ cout<<“Hello”;
if(vec.size()==0){vec.push_back(prev->val);vec.push_back(A->val);}
if(vec.size()==2){vec1=A->val;}
}
}
prev=A;
iit(A->right,prev);
}

vector Solution::recoverTree(TreeNode* A)
{
vec.clear();
TreeNode* prev=(TreeNode* )malloc(sizeof(TreeNode));
prev=NULL;
iit(A,prev);
sort(vec.begin(),vec.end());
return vec;
}

test case:
535 344 162 345 152 181 -1 -1 106 161 173 261 92 133 157 -1 165 178 256 329 86 104 108 137 154 160 163 171 174 179 210 258 265 335 83 87 102 105 107 114 134 147 153 155 159 -1 -1 164 170 172 -1 176 -1 180 182 221 257 259 264 311 334 337 80 85 -1 90 96 103 -1 -1 -1 -1 109 132 -1 135 144 148 -1 -1 -1 156 158 -1 -1 -1 167 -1 -1 -1 175 177 -1 -1 -1 202 219 223 -1 -1 -1 260 262 -1 278 314 331 -1 336 339 79 82 84 -1 88 91 93 97 -1 -1 -1 113 117 -1 -1 136 139 145 -1 150 -1 -1 -1 -1 166 168 -1 -1 -1 -1 186 208 214 220 222 245 -1 -1 -1 263 269 304 313 319 330 333 -1 -1 338 341 -1 -1 81 -1 -1 -1 -1 89 -1 -1 -1 95 -1 98 110 -1 115 125 -1 -1 138 141 -1 146 149 151 -1 -1 -1 169 185 193 203 209 213 218 -1 -1 -1 -1 241 247 -1 -1 268 276 297 307 312 -1 317 328 -1 -1 332 -1 -1 -1 340 343 -1 -1 -1 -1 94 -1 -1 99 -1 111 116 -1 120 128 -1 -1 140 142 -1 -1 -1 -1 -1 -1 -1 -1 184 -1 192 198 -1 206 -1 -1 211 -1 215 -1 224 244 246 250 267 -1 275 277 291 299 306 308 -1 -1 316 318 320 -1 -1 -1 -1 -1 342 -1 -1 -1 -1 101 -1 112 -1 -1 118 122 126 130 -1 -1 -1 143 183 -1 189 -1 195 200 205 207 -1 212 -1 217 -1 227 243 -1 -1 -1 248 251 266 -1 274 -1 -1 -1 281 295 298 301 305 -1 -1 309 315 -1 -1 -1 -1 323 -1 -1 100 -1 -1 -1 -1 119 121 124 -1 127 129 131 -1 -1 -1 -1 187 190 194 196 199 201 204 -1 -1 -1 -1 -1 216 -1 226 239 242 -1 -1 249 -1 253 -1 -1 270 -1 280 290 294 296 -1 -1 300 302 -1 -1 -1 310 -1 -1 321 325 -1 -1 -1 -1 -1 -1 123 -1 -1 -1 -1 -1 -1 -1 -1 188 -1 191 -1 -1 -1 197 -1 -1 -1 -1 -1 -1 -1 -1 225 -1 231 240 -1 -1 -1 -1 252 254 -1 272 279 -1 283 -1 292 -1 -1 -1 -1 -1 -1 303 -1 -1 -1 322 324 327 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 228 232 -1 -1 -1 -1 -1 255 271 273 -1 -1 282 284 -1 293 -1 -1 -1 -1 -1 -1 326 -1 -1 229 -1 238 -1 -1 -1 -1 -1 -1 -1 -1 -1 285 -1 -1 -1 -1 -1 230 237 -1 -1 287 -1 -1 235 -1 286 288 233 236 -1 -1 -1 289 -1 234 -1 -1 -1 -1 -1 -1