- class Demo
- {
- public static void main(String[] args)
- {
- int[] arr = new int[]{1,6,9,11,18,54,60,66,90};
- System.out.println("insert 19 to array:");
- printArr(arr);
- int[] newArr = insert( arr, 100 );
- printArr( newArr );
- }
- //打印一个数组
- public static void printArr(int[] arr)
- {
- for (int x = 0; x<arr.length; x++ )
- {
- if (x == arr.length - 1)
- {
- System.out.println(arr[x]);
- break;
- }
- System.out.print(arr[x] + "\t");
- }
- }
- //在数组中插入一个元素
- public static int[] insert( int[] arr, int insertKey )
- {
-
- int loc, mid;
- int[] newArr = new int[arr.length + 1];
- mid = locFind( arr, insertKey );
- //插入新元素操作,分三种情况,在首部,在尾部,在中间
- if (insertKey < arr[0])//在首部
- {
- newArr[0] = insertKey;
- for ( int x = 1; x <= arr.length; x++ )
- {
- newArr[x] = arr[x - 1];
- }
- }
- else if (insertKey > arr[arr.length - 1])//在尾部
- {
- int x;
- for (x = 0 ; x < arr.length ; x++ )
- {
- newArr[x] = arr[x];
- }
- newArr[x] = insertKey;
- }
- else//在中间
- {
- for ( loc = 0; loc <= mid; loc++ )//插入位之前的元素赋值给新数组
- {
- newArr[loc] = arr[loc];
- }
- newArr[loc] = insertKey;
-
- for ( loc++; loc < newArr.length; loc++ )//插入位之后的元素赋值给新数组
- {
- newArr[loc] = arr[loc - 1];
- }
- }
- return newArr;
- }
- //用折半查找法找到元素应该插入数组的位置并返回
- public static int locFind( int[] arr, int insertKey )
- {
- int min, mid, max;
- min = 0;
- max = arr.length;
- mid = ( max + min ) / 2;
- while ( min < max )
- {
- if ( insertKey > arr[mid] )
- {
- min = mid + 1;
- }
- else if ( insertKey < arr[mid] )
- {
- max = mid - 1;
- }
- mid = ( max + min ) / 2;
- }
- return mid;
- }
- }
复制代码 经过我的修改,代码已经可以实现了,原来要分成三种情况来判断插入的位置~
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