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 :
Input: n = 10, pick = 6 Output: 6
package leetcode.easy;
/* 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); */
class GuessGame {
public int guess(int num) {
if (6 > num) {
return -1;
} else if (6 == num) {
return 0;
} else {
return 1;
}
}
}
public class GuessNumberHigherOrLower extends GuessGame {
public int guessNumber1(int n) {
for (int i = 1; i < n; i++) {
if (guess(i) == 0) {
return i;
}
}
return n;
}
public int guessNumber2(int n) {
int low = 1;
int high = n;
while (low <= high) {
int mid = low + (high - low) / 2;
int res = guess(mid);
if (res == 0) {
return mid;
} else if (res < 0) {
high = mid - 1;
} else {
low = mid + 1;
}
}
return -1;
}
public int guessNumber3(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;
}
@org.junit.Test
public void test() {
GuessNumberHigherOrLower guessNumberHigherOrLower = new GuessNumberHigherOrLower();
System.out.println(guessNumberHigherOrLower.guessNumber1(10));
System.out.println(guessNumberHigherOrLower.guessNumber2(10));
System.out.println(guessNumberHigherOrLower.guessNumber3(10));
}
}