// Description

// The code base version is an integer start from 1 to n.One day, someone committed a bad version in the code case, so it caused this version and the following versions are all failed in the unit tests.Find the first bad version.

// You can call isBadVersion to help you determine which version is the first bad one.The details interface can be found in the code's annotation part.

// Example:

// Given n = 5, and version = 4 is the first bad version.

// call isBadVersion(3) -> false

// call isBadVersion(5) -> true

// call isBadVersion(4) -> true

// 1 2 3 4 5 6

// O O O X X X

// Then 4 is the first bad version.

/**

* @param {integer} n Total versions

* @return {integer} The first bad version

*/

const solution = isBadVersion => n => {

let start = 1, end = n, mid

while (start + 1 < end) {

mid = start + Math.floor((end - start) / 2)

if (isBadVersion(mid)) {

end = mid

} else {

start = mid

}

}

if (isBadVersion(start)) return start

// if (isBadVersion(end)) return end

return end // 保证有解

}

// 二刷

/*

tips:

1 错误点：审题。是 find the fisrt TRUE. isBadVersion 返回值为true的。

2

const solution = isBadVersion => n => {} 相当于

var solution = function(isBadVersion) {

return function (n) {

};

};

*/