CODEWITHSUNDEEP
c++vectorlower-bound
MrRobot9
MrRobot9

Reputation: 2684

lower_bound(v.begin(), v.end(), x)

I am a noob to c++, I just came across this code

       x = v[lft]+k;
       low = lower_bound(v.begin(), v.end(), x) - v.begin();

       if(low >= n|| v[low] > x )
        low--;
       center = v[low];

if x is not present in the vector, it returns a value greater than the size of the vector. That justifies searching whether low >= n , but I cant figure out under which circumstance will this condition v[low] > x satisy?Should'nt low be an index in which x is present, so how can there be a value greater than x?

Upvotes: 0

Views: 830

Answers (1)

Jonathan Lee
Jonathan Lee

Reputation: 517

lower_bound returns

an iterator pointing to the first element in the range [first, last) that is not less than (i.e. greater or equal to) value.

See here for more detail: lower_bound - cppreference

Upvotes: 2

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