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Copy pathSolution.java
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49 lines (46 loc) · 1.44 KB
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package binarySearch;
import org.junit.Assert;
import org.junit.Test;
/**
* 给定一个 n 个元素有序的（升序）整型数组 nums 和一个目标值 target ，写一个函数搜索 nums 中的 target，如果目标值存在返回下标，否则返回 -1。
*/
public class Solution {
public int search(int[] nums, int target) {
int start = 0, end = nums.length - 1;
while (start <= end) {// 注意判断条件
int mid = start + (end - start)/2;
if (target == nums[mid]){
return mid;
} else if (nums[mid] > target){
end = mid - 1; // 是mid - 1不是mid
}else {
start = mid + 1; // 是mid + 1不是mid
}
}
return -1;
}
@Test
public void Test1(){
Assert.assertTrue(search(new int[]{-1, 0, 3, 5, 9, 12}, -1) == 0);
}
@Test
public void Test2(){
Assert.assertTrue(search(new int[]{-1, 0, 3, 5, 9, 12}, 0) == 1);
}
@Test
public void Test3(){
Assert.assertTrue(search(new int[]{-1, 0, 3, 5, 9, 12}, 3) == 2);
}
@Test
public void Test4(){
Assert.assertTrue(search(new int[]{-1, 0, 3, 5, 9, 12}, 5) == 3);
}
@Test
public void Test5(){
Assert.assertTrue(search(new int[]{-1, 0, 3, 5, 9, 12}, 9) == 4);
}
@Test
public void Test6(){
Assert.assertTrue(search(new int[]{-1, 0, 3, 5, 9, 12}, 12) == 5);
}
}