[LeetCode]374. Guess Number Higher or Lower【&375. Guess Number Higher or Lower II】

374 . Guess Number Higher or Lower
Easy

We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I’ll tell you whether the number is higher or lower.

You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):

-1 : My number is lower
1 : My number is higher
0 : Congrats! You got it!
Example:
n = 10, I pick 6.

Return 6.

2ms:

public int guessNumber(int n) {         if (guess(n) == 0) return n;         int left = 1, right = n;         while (left < right) {             int mid = left + (right - left) / 2, t = guess(mid);             if (t == 0) return mid;              else if (t == 1) left = mid;             else right = mid;         }         return left;     }

1ms:

 public int guessNumber(int n) {         if(guess(n)==0) return n;         int leftp=1;         int rip=n;         int mid = gg(leftp,rip);         int res = guess(mid);         while(res!=0){             if(res<0)                 rip=mid;             else                 leftp=mid;             mid=gg(leftp,rip);             res=guess(mid);         }         return mid;     }     int gg(int le,int rh){return (rh-le)/2 + le;}

对照[LeetCode]278. First Bad Version

375 . Guess Number Higher or Lower II
Medium

We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I’ll tell you whether the number I picked is higher or lower.

However, when you guess a particular number x, and you guess wrong, you pay $x. You win the game when you guess the number I picked.

Example:

n = 10, I pick 8.

First round: You guess 5, I tell you that it’s higher. You pay 5.Secondround:Youguess7,Itellyouthatit′shigher.Youpay7.
Third round: You guess 9, I tell you that it’s lower. You pay $9.

Game over. 8 is the number I picked.

You end up paying 5+7 + 9=21.
Given a particular n ≥ 1, find out how much money you need to have to guarantee a win.