二分查找

/**
 * @param{number[]}nums
 * @param{number}target
 * @return{number}
 */
var search = function(nums, target) {
  let left=0,right=nums.length-1
  while(left<right){
    let middle = Math.floor(right/2+left/2);
    if(nums[middle]<target){
      left = middle+1
     }
    else{
      right=middle
     }
   }
  if(nums[left]==target){
    return left
     }
  else{
    return -1
   }
};

/**
 * 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
     */
    return function(n) {
        let left=1,right=n
        while(left<right){
            let middle=Math.floor(left/2+right/2)
            if(isBadVersion(middle)){
               right=middle
            }
            else{
                left=middle+1
            }
        }
        return left
    };
};

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number}
 */
var searchInsert = function(nums, target) {
    let left=0,right=nums.length-1
    while(left<right){
        let middle=Math.floor(left/2+right/2)
        if(nums[middle]<target){
            left=middle+1
        }
        else right=middle
    }
    if (nums[right]<target){
        return left+1
    }
    else{
        return left
    }
};