int?dfs(int?i,?int?j,?int?m,?int?n)?

{????????

if?(i?>?m?||?j?>?n)?return?0;?//?越界了????????

if?(i?==?m?&&?j?==?n)?return?1;?

//?找到一種方法，相當于找到了葉子節點????????

return?dfs(i?+?1,?j,?m,?n)?+?dfs(i,?j?+?1,?m,?n);???

?}

?int?uniquePaths(int?m,?int?n)?

{????????

return?dfs(1,?1,?m,?n);????

}

?