出现次数top K的进阶问题

红太狼 2022-05-26 02:09 148阅读 0赞

![70][]

import java.util.HashMap;
    //出现次数top K的进阶问题
    public class TopKAdvanceProblem{
        //堆节点定义
        public static class Node {
            public String str;
            public int times;
    
            public Node(String s, int t) {
                str = s;
                times = t;
            }
        }
       //TopK的记录
        public static class TopKRecord {
            private Node[] heap;
            private int index;
            private HashMap<String, Node> strNodeMap;
            private HashMap<Node, Integer> nodeIndexMap;
    
            public TopKRecord(int size) {
                heap = new Node[size];
                index = 0;
                strNodeMap = new HashMap<String, Node>();
                nodeIndexMap = new HashMap<Node, Integer>();
            }
    
        public void add(String str) {
                Node curNode = null;
                int preIndex = -1;
                if (!strNodeMap.containsKey(str)) {
                    curNode = new Node(str, 1);
                    strNodeMap.put(str, curNode);
                    nodeIndexMap.put(curNode, -1);
                } else {
                    curNode = strNodeMap.get(str);
                    curNode.times++;
                    preIndex = nodeIndexMap.get(curNode);
                }
                if (preIndex == -1) {
                    if (index == heap.length) {
                        if (heap[0].times < curNode.times) {
                            nodeIndexMap.put(heap[0], -1);
                            nodeIndexMap.put(curNode, 0);
                            heap[0] = curNode;
                            heapify(0, index);
                        }
                    } else {
                        nodeIndexMap.put(curNode, index);
                        heap[index] = curNode;
                        heapInsert(index++);
                    }
                } else {
                    heapify(preIndex, index);
                }
            }
        //获得top k的数
        public void printTopK() {
                System.out.println("TOP: ");
                for (int i = 0; i != heap.length; i++) {
                    if (heap[i] == null) {
                        break;
                    }
                    System.out.print("Str: " + heap[i].str);
                    System.out.println(" Times: " + heap[i].times);
                }
            }
        //向堆中添加数据
        private void heapInsert(int index) {
                while (index != 0) {
                    int parent = (index - 1) / 2;
                    if (heap[index].times < heap[parent].times) {
                        swap(parent, index);
                        index = parent;
                    } else {
                        break;
                    }
                }
            }
        //堆调整
        private void heapify(int index, int heapSize) {
                int l = index * 2 + 1;
                int r = index * 2 + 2;
                int smallest = index;
                while (l < heapSize) {
                    if (heap[l].times < heap[index].times) {
                        smallest = l;
                    }
                    if (r < heapSize && heap[r].times < heap[smallest].times) {
                        smallest = r;
                    }
                    if (smallest != index) {
                        swap(smallest, index);
                    } else {
                        break;
                    }
                    index = smallest;
                    l = index * 2 + 1;
                    r = index * 2 + 2;
                }
            }
    
        private void swap(int index1, int index2) {
                nodeIndexMap.put(heap[index1], index2);
                nodeIndexMap.put(heap[index2], index1);
                Node tmp = heap[index1];
                heap[index1] = heap[index2];
                heap[index2] = tmp;
            }
    
        }
       //获得随机大小的数组
        public static String[] generateRandomArray(int len, int max) {
            String[] res = new String[len];
            for (int i = 0; i != len; i++) {
                res[i] = String.valueOf((int) (Math.random() * (max + 1)));
            }
            return res;
        }
        //打印数组
        public static void printArray(String[] arr) {
            for (int i = 0; i != arr.length; i++) {
                System.out.print(arr[i] + " ");
            }
            System.out.println();
        }
        public static void main(String[]args){
            TopKRecord record = new TopKRecord(2);
            record.add("zuo");
            record.printTopK();  //打印 topk 
            record.add("chao");
            record.add("chao");
            record.add("chao");
            record.printTopK(); //打印 topk 
            record.add("ren");
            record.add("ren");
            record.printTopK();//打印 topk 
    
        }
    }

![70 1][]

[70]: /images/20220526/f833ceb560764018a6a363c4be30d0b3.png
[70 1]: /images/20220526/a887347046d947c5a534ffa7fd243af1.png