如果你40pts，只对了测试点1,2,3,5,那大概率是因为数据包含0，离散化出问题了

for(int i = 1;i <= n;i ++){
  if(b[i] != b[i-1]){
    mp[b[i]] = ++tmp;
    dmp[tmp] = b[i];
  }
}//源码

应该加上

b[0] = -1;