题目描述
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 6.二分法
# The guess API is already defined for you.
# @param num, your guess
# @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
# def guess(num):
class Solution(object):
def guessNumber(self, n):
"""
:type n: int
:rtype: int
"""
low = 1
high = n
while low <= high:
mid = (low + high) // 2
res = guess(mid)
if res == 0:
return mid
elif res == -1:
high = mid - 1
else:
low = mid + 1三分法
/* The guess API is defined in the parent class GuessGame.
@param num, your guess
@return -1 if my number is lower, 1 if my number is higher, otherwise return 0
int guess(int num); */
public class Solution extends GuessGame {
public int guessNumber(int n) {
int low = 1;
int high = n;
while (low <= high) {
int mid1 = low + (high - low) / 3;
int mid2 = high - (high - low) / 3;
int res1 = guess(mid1);
int res2 = guess(mid2);
if (res1 == 0)
return mid1;
if (res2 == 0)
return mid2;
else if (res1 < 0)
high = mid1 - 1;
else if (res2 > 0)
low = mid2 + 1;
else {
low = mid1 + 1;
high = mid2 - 1;
}
}
return -1;
}
}