Guess Number Higher or Lower

1/** 
2 * Forward declaration of guess API.
3 * @param  num   your guess
4 * @return 	     -1 if num is higher than the picked number
5 *			      1 if num is lower than the picked number
6 *               otherwise return 0
7 * int guess(int num);
8 */
9
10 public class Solution extends GuessGame {
11    public int guessNumber(int n) {
12        int lower = 1;
13        int higher = n;
14        while (lower <= higher) {
15            // This simplified expression will cause time limit exceeded.
16            // So either use long, or rewrite in a form that doesn't risk overflow.
17            // int mid = (higher + lower) / 2;
18            int mid = lower + (higher - lower) / 2;
19            int result = guess(mid);
20            if (result == 0) {
21                return mid;
22            }
23            else if (result > 0) {
24                lower = mid + 1;
25            }
26            else if (result < 0) {
27                higher = mid - 1;
28            }
29        }
30        return 0;
31    }
32}

1/** 
2 * Forward declaration of guess API.
3 * @param  num   your guess
4 * @return 	     -1 if num is higher than the picked number
5 *			      1 if num is lower than the picked number
6 *               otherwise return 0
7 * unsafe fn guess(num: i32) -> i32 {}
8 */
9
10 impl Solution {
11  unsafe fn guessNumber(n: i32) -> i32 {
12      let mut lower = 1;
13      let mut higher = n;
14
15      while lower <= higher {
16          let mut mid = lower + (higher - lower) / 2;
17          let result = guess(mid);
18
19          if result == 0 {
20              return mid;
21          }
22          else if result > 0 {
23              lower = mid + 1;
24          }
25          else { // result < 0
26              higher = mid - 1;
27          }
28      }
29
30      return 0;
31  }
32}