std vector erase 방법 두 가지
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std::vector<int> v;
for (int i = 0; i < v.size(); i++) {
if (n == v[i]) {
v.erase(v.begin()+i);
}
}
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// iterator
for(auto it; it != v.end(); it++) {
if(n==*it)
it = v.erase(it);
}