import java.util.Scanner;
public class Ch1_1 {
public static void main(String[] args) {
int[] array = {1,2,3,6,9,10,13,16,45,56};
Scanner scn = new Scanner(System.in);
while (scn.hasNext()) {
int number = scn.nextInt();
// 顺序查找
System.out.println("lineSearch index:"+lineSearch(array, number));
// 二分查找
System.out.println("lineSearch index:"+binarySearch(array, number));
}
}
// 顺序查找法, 逐个查找, 时间复杂度n
public static int lineSearch(int[] array, int number) {
int index = -1;
for (int i=0;i<array.length;i++) {
if (array[i] == number) {
index = i;
break;
}
}
return index;
}
// 二分查找法, 也称折半查找, 限定为有序数列, 时间复杂度O(log2n)
public static int binarySearch(int[] array, int number) {
int start = 0;
int end = array.length-1;
int mid = end / 2;
int index = -1;
while (start <= end) {
if (array[mid] == number) {
index = mid;
break;
} else if (array[mid] > number) {
end = mid -1;
mid = (start + end)/2;
} else {
start = mid +1;
mid = (start + end)/2;
}
}
return index;
}
}
参考文献:
[1] Data Structure & Algorithm七大查找算法 - Poll的笔记 - 博客园