[자바스크립트로 구현한 알고리즘] Find the next perfect square!

Description: 

You might know some pretty large perfect squares. But what about the NEXT one? Complete the findNextSquare method that finds the next integral perfect square after the one passed as a parameter. Recall that an integral perfect square is an integer n such that sqrt(n) is also an integer. If the parameter is itself not a perfect square, than -1 should be returned. You may assume the parameter is positive. 

Examples: 

findNextSquare(121) --> returns 144 

findNextSquare(625) --> returns 676 

findNextSquare(114) --> returns -1 

since 114 is not a perfect

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