二分查找法
废话不多说,直接上代码
public static void main(String[] args) {
int srcArray[] = {3,5,11,17,21,23,28,30,32,50,64,78,81,95,101};
System.out.println(binSearch(srcArray, 0, srcArray.length -1, 81));
}
// 二分查找递归实现
public static int binSearch(int srcArray[], int start, int end, int key) {
int mid = (end - start) /2 + start;
if (srcArray[mid] == key) {
return mid;
}
if (start >= end) {
return -1;
}else if (key > srcArray[mid]) {
return binSearch(srcArray, mid +1, end, key);
}else if (key < srcArray[mid]) {
return binSearch(srcArray, start, mid -1, key);
}
return -1;
}
// 二分查找普通循环实现
public static int binSearch(int srcArray[], int key) {
int mid = srcArray.length /2;
if (key == srcArray[mid]) {
return 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;
}
