标 题: 一道linkedin常见题，我的答案对吗？
Consider an X x Y array of 1's and 0s. The X axis represents "influences"
meaning that X influences Y. So, for example, if $array[3,7] is 1 that means
that 3 influences 7.
An "influencer" is someone who influences every other person, but is not
influenced by any other member.
Given such an array, write a function to determine whether or not an
"influencer" exists in the array.