牛客网暑期ACM多校训练营(第一场)A.Monotonic Matrix(非降路径和Lindström–Gessel–Viennot定理)
链接:https://www.nowcoder.com/acm/contest/139/A来源:牛客网题目描述CountthenumberofnxmmatricesAsatisfyingthefollowingconditionmodulo(109+7).*Ai,j∈{0,1,2}forall1≤i≤n,1≤j≤m.*Ai,j≤Ai+1,jforall1≤i(0,m)(n,0)−>(0,m)如果不