View Compilation Error

0_0_25479806_14779.cpp: In function 'void dfs(int)':
0_0_25479806_14779.cpp:37:11: error: 'i' was not declared in this scope
     dfs(t[i].r);
           ^
0_0_25479806_14779.cpp: In function 'int main()':
0_0_25479806_14779.cpp:53:45: error: invalid types 'int[int]' for array subscript
         for(int i=1;i<=n;i++)scanf("%d",&t[i].val);
                                             ^
0_0_25479806_14779.cpp:54:25: error: invalid types 'int[int]' for array subscript
         build(n);dfs(t[0].r);
                         ^
0_0_25479806_14779.cpp:56:45: error: invalid types 'int[int]' for array subscript
         for(int i=1;i<=n;i++)ans=ans*inv[t[i].sz]%mod;
                                             ^