View Compilation Error

0_0_16694787_29115.cpp: In function 'void update(int*)':
0_0_16694787_29115.cpp:23:5: error: 'ans' was not declared in this scope
     ans=max(ans,sum);  
     ^
0_0_16694787_29115.cpp: In function 'void dfs(int, int*)':
0_0_16694787_29115.cpp:26:8: error: 'n' was not declared in this scope
     if(n==0) return 0;
        ^
0_0_16694787_29115.cpp:26:21: error: return-statement with a value, in function returning 'void' [-fpermissive]
     if(n==0) return 0;
                     ^