easy short efficient clean code
\nclass Solution {\npublic:\ntypedef long long ll;\nlong long findTheArrayConcVal(vector<int>&v) {\n    ll n=v.size(), ans=0, l=0, r=n-1;\n    while(l<r){\n    
```\nclass Solution {\npublic:\ntypedef long long ll;\nlong long findTheArrayConcVal(vector<int>&v) {\n    ll n=v.size(), ans=0, l=0, r=n-1;\n    while(l<r){\n        ans+=stoll(to_string(v[l++])+to_string(v[r--]));\n    }\n    if(l==r){\n        ans+=v[l];\n    }\n    return ans;\n}\n};\n```
['C']