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SearchRotatedArray.java
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SearchRotatedArray.java
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package com.eprogrammerz.examples.algorithm.leetcode;
import org.junit.Test;
import static org.junit.Assert.assertEquals;
/**
* Suppose an array sorted in ascending order is rotated at some pivot unknown to you beforehand.
* <p>
* (i.e., [0,1,2,4,5,6,7] might become [4,5,6,7,0,1,2]).s
* <p>
* Input: nums = [4,5,6,7,0,1,2], target = 0
* Output: 4
* <p>
* <p>
* https://leetcode.com/problems/search-in-rotated-sorted-array/
*/
public class SearchRotatedArray {
public int search(int[] nums, int target) {
int start = 0;
int end = nums.length - 1;
while (start <= end) {
int mid = start + (end - start) / 2;
if (nums[mid] == target) return mid;
// if left part is sorted
if (nums[start] <= nums[mid]) {
// make sure target falls in sorted part
if (nums[start] <= target && target < nums[mid]) {
end = mid - 1;
} else {
start = mid + 1;
}
} else {
if (nums[mid] < target && target <= nums[end]) {
start = mid + 1;
} else {
end = mid - 1;
}
}
}
return -1;
}
@Test
public void test1() {
assertEquals(0, search(new int[]{4, 5, 6, 7, 0, 1, 2}, 4));
assertEquals(1, search(new int[]{4, 5, 6, 7, 0, 1, 2}, 5));
assertEquals(2, search(new int[]{4, 5, 6, 7, 0, 1, 2}, 6));
assertEquals(3, search(new int[]{4, 5, 6, 7, 0, 1, 2}, 7));
assertEquals(4, search(new int[]{4, 5, 6, 7, 0, 1, 2}, 0));
assertEquals(5, search(new int[]{4, 5, 6, 7, 0, 1, 2}, 1));
assertEquals(6, search(new int[]{4, 5, 6, 7, 0, 1, 2}, 2));
}
@Test
public void test2() {
assertEquals(4, search(new int[]{4, 5, 6, 7, 8, 1, 2, 3}, 8));
}
@Test
public void test3() {
assertEquals(1, search(new int[]{3, 1}, 1));
}
}