Question

用Java写一个小程序判断一个数组是不是heap

Answer 1

挺简单的啊。。 关键在于理解heap
import java.util.Arrays;

public class Du {

public static void main(String[] args) {

int[] testAry1 = {1, 3, 5, 7, 9, 11};
System.out.println("{1, 3, 5, 7, 9, 11} is " + (isHeap(testAry1)? "": "NOT ") + "heap array.");

int[] testAry2 = {1, 3, 5, 7, 13, 9, 11};
System.out.println("{1, 3, 5, 7, 13, 9, 11} is " + (isHeap(testAry2)? "":"NOT ") + "heap array.");

}

/**
* Will receive an integer heap array, method will return true or false
* depending on whether the array is believed to be a valid heap or not
*
* @param heap
* 0-based integer array
* @return true if integer array is a heap, else false
*/
public static boolean isHeap(int[] heap) {

if(heap == null || heap.length == 0){
return false;
}

int[] ary = new int[heap.length];

for(int i = 0; i < heap.length; i++){
ary[i] = heap[i];
}

Arrays.sort(ary);

for(int i = 0; i < heap.length; i++){
if(ary[i] != heap[i]){
return false;
}
}

return true;
}
}

---------------
{1, 3, 5, 7, 9, 11} is heap array
{1, 3, 5, 7, 13, 9, 11} is NOT heap array

Answer 2

我也同等.

Answer 3

是大根堆还是小根堆?

追问

只要判断是不是heap就可以了 就是满足最小的在最上面 每一个节点的孩子比他大