Method put

code/other/two_sat.cpp:8–9

      V[i].adj.clear(),
      V[i].val = V[i].num = -1, V[i].done = false; }
  bool put(int x, int v) {
    return (V[n+x].val &= v) != (V[n-x].val &= 1-v); }
  void add_or(int x, int y) {
    V[n-x].adj.push_back(n+y), V[n-y].adj.push_back(n+x); }
  int dfs(int u) {