查看原题'" class='mdui-btn mdui-btn-raised'>点击加载点击跳转$f_{i,j,k,(1/0)}$：$a_i$(选或不选)$,b_j,$第$k$位$f{i,j,k,0} = f{i-1,j,k,0} + f_{i-1,j,k,1}$$a_i = b_j$:$$f{i,j,k,1}=f{i-1,j-1,k,1}+f{i-1,j-1,k-1,0}+f{i-1,j-1,k-1,1}$$$a_i = b_j$:$f_{i,j,k,1} = 0$……