• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• 24
• 25
• 26
• 27
• 28
• 29
• 30
• 31
• 32
• 33
• 34
• 35
• 36
• 37
• 38
• 39
• 40
• 41
• 42
• 43
• 44
• 45
• 46
• 47
• 48
• 49
• 50
• 51
• 52
• 53
• 54
• 55
• 56
• 57
• 58
• 59
• 60
• 61
• 62
• 63
• 64
• 65

/**
 * Definition for isBadVersion()
 * 
 * @param {integer} version number
 * @return {boolean} whether the version is bad
 * isBadVersion = function(version) {
 *     ...
 * };
 */

/**
 * @param {function} isBadVersion()
 * @return {function}
 */
var solution = function(isBadVersion) {
    /**
     * @param {integer} n Total versions
     * @return {integer} The first bad version
     */
    let index = 0
    
                    
    return function(t) {
        let middle = Math.ceil(t/2);
        let lastMiddle = 20
        
        
        /**
            total 20
            bad 17
            lastM = 20
            
            (20 - lastM(20)) /2 == 10 // first time, just 20/2 (cause (20 - 20) / 2  [ 0/2]!!)

            (20 - lastM(10)) /2 === 15
            (20 - lastM(15) ) / 2 === 13 // WRONG WAY
            
            lastGood = 17
            lastBad = 15
            
    
            Pick middle: t / 2 === 10
            isBad(10)
                false:
                    lastGood = 10
                    isBad(15)  // middle.= middle + middle/2 (m = 10 + 5 == 15)
                        false:
                            lastGood = 15
                            isBad(18) // m = (20 - 15) / 2 == 5 /2 == 3
                                true: // between 15 and 18 is first bad. set t to 18
                                lastBad = 18
                                    isBad(17) // m = (18 - 15) /2 === 3/2 == 2 
                                        true:
                                            lastBad = 17
                                            isBad(16)
                                
            isBad(10):
                false:
                    lastBad = 10
                                
        */
  
       
    };
};