猜数字游戏的规则如下:
- 每轮游戏,我都会从 1 到 n 随机选择一个数字。 请你猜选出的是哪个数字。
- 如果你猜错了,我会告诉你,你猜测的数字比我选出的数字是大了还是小了。
你可以通过调用一个预先定义好的接口 int guess(int num)
来获取猜测结果,返回值一共有 3 种可能的情况(-1
,1
或 0
):
- -1:我选出的数字比你猜的数字小
pick < num
- 1:我选出的数字比你猜的数字大
pick > num
- 0:我选出的数字和你猜的数字一样。恭喜!你猜对了!
pick == num
返回我选出的数字。
示例 1:
输入:n = 10, pick = 6 输出:6
示例 2:
输入:n = 1, pick = 1 输出:1
示例 3:
输入:n = 2, pick = 1 输出:1
示例 4:
输入:n = 2, pick = 2 输出:2
提示:
1 <= n <= 231 - 1
1 <= pick <= n
方法一:二分查找
我们在区间 guess(x) <= 0
的数,即为答案。
时间复杂度
# 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: int) -> int:
class Solution:
def guessNumber(self, n: int) -> int:
left, right = 1, n
while left < right:
mid = (left + right) >> 1
if guess(mid) <= 0:
right = mid
else:
left = mid + 1
return left
# The guess API is already defined for you.
# @param num, your guess
# @return -1 if num is higher than the picked number
# 1 if num is lower than the picked number
# otherwise return 0
# def guess(num: int) -> int:
class Solution:
def guessNumber(self, n: int) -> int:
return bisect.bisect(range(1, n + 1), 0, key=lambda x: -guess(x))
/**
* Forward declaration of guess API.
* @param num your guess
* @return -1 if num is lower than the guess number
* 1 if num is higher than the guess number
* otherwise return 0
* int guess(int num);
*/
public class Solution extends GuessGame {
public int guessNumber(int n) {
int left = 1, right = n;
while (left < right) {
int mid = (left + right) >>> 1;
if (guess(mid) <= 0) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
}
}
/**
* Forward declaration of guess API.
* @param num your guess
* @return -1 if num is lower than the guess number
* 1 if num is higher than the guess number
* otherwise return 0
* int guess(int num);
*/
class Solution {
public:
int guessNumber(int n) {
int left = 1, right = n;
while (left < right) {
int mid = left + ((right - left) >> 1);
if (guess(mid) <= 0) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
}
};
/**
* Forward declaration of guess API.
* @param num your guess
* @return -1 if num is lower than the guess number
* 1 if num is higher than the guess number
* otherwise return 0
* func guess(num int) int;
*/
func guessNumber(n int) int {
left, right := 1, n
for left < right {
mid := (left + right) >> 1
if guess(mid) <= 0 {
right = mid
} else {
left = mid + 1
}
}
return left
}
/**
* Forward declaration of guess API.
* @param num your guess
* @return -1 if num is higher than the picked number
* 1 if num is lower than the picked number
* otherwise return 0
* func guess(num int) int;
*/
func guessNumber(n int) int {
return sort.Search(n, func(i int) bool {
i++
return guess(i) <= 0
}) + 1
}
/**
* Forward declaration of guess API.
* @param num your guess
* @return -1 if num is higher than the picked number
* 1 if num is lower than the picked number
* otherwise return 0
* int guess(int num);
*/
public class Solution : GuessGame {
public int GuessNumber(int n) {
int left = 1, right = n;
while (left < right) {
int mid = left + ((right - left) >> 1);
if (guess(mid) <= 0) {
right = mid;
} else {
left = mid + 1;
}
}
return left;
}
}
/**
* Forward declaration of guess API.
* @param {number} num your guess
* @return -1 if num is lower than the guess number
* 1 if num is higher than the guess number
* otherwise return 0
* var guess = function(num) {}
*/
function guessNumber(n: number): number {
let l = 1;
let r = n;
while (l < r) {
const mid = (l + r) >>> 1;
if (guess(mid) <= 0) {
r = mid;
} else {
l = mid + 1;
}
}
return l;
}
/**
* Forward declaration of guess API.
* @param num your guess
* @return -1 if num is lower than the guess number
* 1 if num is higher than the guess number
* otherwise return 0
* unsafe fn guess(num: i32) -> i32 {}
*/
impl Solution {
unsafe fn guessNumber(n: i32) -> i32 {
let mut l = 1;
let mut r = n;
loop {
let mid = l + (r - l) / 2;
match guess(mid) {
-1 => r = mid - 1,
1 => l = mid + 1,
_ => break mid,
}
}
}
}