AT_agc061_d [AGC061D] Almost Multiplication Table题解非常好的构造题!山东省集被出了。应该通俗易懂吧……考虑二分答案 m i d mid mid,设 L i , j = a i , j − m i d L_{i,j}=a_{i,j}-mid Li,j=ai,j−mid, R i , j = a i , j + m i d R_{i,j}=a_{i,j}+mid Ri,j=ai,j+mid,则 X i Y j ∈ [ L i , j , R i , j ] X_iY_j\in [L_{i,j},R_{i,j}] XiYj∈[Li,j,Ri,j]。我们只需要判断