二分查找算法（遞歸與非遞歸兩種方式）
非遞歸方式完成二分查找法。java代碼如下所示。
public class BinarySearchUtil {
/**
* 二分查找普通實現。
* @param srcArray 有序數組
* @param key 查找元素
* @return 不存在返回-1
*/
public static int binSearch(int srcArray[], int key) {
int mid;
int start = 0;
int end = srcArray.length - 1;
while (start <= end) {
mid = (end - start) / 2 + start;
if (key < srcArray[mid]) {
end = mid - 1;
} else if (key > srcArray[mid]) {
start = mid + 1;
} else {
return mid;
}
}
return -1;
}
public static void main(String[] args) {
int srcArray[] = {3,13,23,33,43,53,63,73,83,93,103,203,303,403,1003};
System.out.println(binSearch(srcArray,81));
}
}
採用遞歸方式完成二分查找算法。代碼如下所示。
public class BinarySearchUtil {
/**
* 二分查找遞歸實現。
* @param srcArray 有序數組
* @param key 查找元素
* @return 不存在返回-1
*/
public static int binarySearch(int[] shuzu, int numKey, int start, int end) {
int mid = (end - start) / 2 + start;
if (start > end) {
return -1;
}
if (numKey < shuzu[mid]) {
return binarySearch(shuzu, numKey, start, mid - 1);
} else if (numKey > shuzu[mid]) {
return binarySearch(shuzu, numKey, mid + 1, end);
} else {
return mid;
}
}
public static void main(String[] args) {
int srcArray[] = {3,13,23,33,43,53,63,73,83,93,103,203,303,403,1003};
System.out.println(binarySearch(srcArray, 10, 0, srcArray.length - 1));
}
}