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Parsing with istringstream
A std::istringstream turns a string into an input stream, so everything you know about std::cin works on it:
std::istringstream in("12 7 30");
int a, b, c;
in >> a >> b >> c;
The stream converts to false once a read fails, so while (in >> x) reads until the data runs out or hits something that isn't a number. The most common pattern is to read a whole line with std::getline, then parse that line on its own.
Your turn: each input line holds a player name followed by some round scores (possibly none). For each line print NAME TOTAL.