First Repeated Number

Keep a set<int> of the values seen so far.

Write a function int firstRepeat(const vector<int>& v) that scans v from left to right and returns the first value that has already appeared earlier in the vector. If no value ever repeats, return -1.

For example, in {5, 2, 7, 2, 7} the function returns 2.

Do NOT write a main function.

Expected Output:

2↵
-1↵

= newline. The output ends with a newline — print one after the last line.

Hints4 available

Topics:

STL ContainersSets

Code Editor

Tab to indent (Esc then Tab to move on) · Ctrl+Enter to run · Shift+Alt+F to format · Ctrl+Space to expand shortcuts (cout, fori)

Your Output

Run your code to see the output here...

Test Cases

Run your code to see test case results.