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| 1 | +/* |
| 2 | + * @lc app=leetcode.cn id=374 lang=java |
| 3 | + * |
| 4 | + * [374] 猜数字大小 |
| 5 | + * |
| 6 | + * https://leetcode-cn.com/problems/guess-number-higher-or-lower/description/ |
| 7 | + * |
| 8 | + * algorithms |
| 9 | + * Easy (44.17%) |
| 10 | + * Likes: 64 |
| 11 | + * Dislikes: 0 |
| 12 | + * Total Accepted: 25.7K |
| 13 | + * Total Submissions: 57.5K |
| 14 | + * Testcase Example: '10\n6' |
| 15 | + * |
| 16 | + * 我们正在玩一个猜数字游戏。 游戏规则如下: |
| 17 | + * 我从 1 到 n 选择一个数字。 你需要猜我选择了哪个数字。 |
| 18 | + * 每次你猜错了,我会告诉你这个数字是大了还是小了。 |
| 19 | + * 你调用一个预先定义好的接口 guess(int num),它会返回 3 个可能的结果(-1,1 或 0): |
| 20 | + * |
| 21 | + * -1 : 我的数字比较小 |
| 22 | + * 1 : 我的数字比较大 |
| 23 | + * 0 : 恭喜!你猜对了! |
| 24 | + * |
| 25 | + * |
| 26 | + * |
| 27 | + * |
| 28 | + * 示例 : |
| 29 | + * |
| 30 | + * 输入: n = 10, pick = 6 |
| 31 | + * 输出: 6 |
| 32 | + * |
| 33 | + */ |
| 34 | + |
| 35 | +// @lc code=start |
| 36 | +/** |
| 37 | + * Forward declaration of guess API. |
| 38 | + * @param num your guess |
| 39 | + * @return -1 if num is lower than the guess number |
| 40 | + * 1 if num is higher than the guess number |
| 41 | + * otherwise return 0 |
| 42 | + * int guess(int num); |
| 43 | + */ |
| 44 | + |
| 45 | +public class Solution extends GuessGame { |
| 46 | + public int guessNumber(int n) { |
| 47 | + int left = 1; |
| 48 | + int right = n; |
| 49 | + while (left <= right) { |
| 50 | + int mid = left + (right - left) / 2; |
| 51 | + if (guess(mid) == -1) { |
| 52 | + right = mid - 1; |
| 53 | + } else if (guess(mid) == 1) { |
| 54 | + left = mid + 1; |
| 55 | + } else if (guess(mid) == 0) { |
| 56 | + return mid; |
| 57 | + } |
| 58 | + } |
| 59 | + return -1; |
| 60 | + } |
| 61 | +} |
| 62 | +// @lc code=end |
| 63 | + |
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