CompleteWinnerTree.hpp

/*
 Copyright (c) 2017 waynezxcv <liuweiself@126.com>
 
 https://github.com/waynezxcv/Playground
 
 
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 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 
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 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 */






#ifndef CompleteWinnerTree_hpp
#define CompleteWinnerTree_hpp

#include <stdio.h>
#include "WinnerTree.hpp"
#include "IllegalParameterValue.hpp"





namespace LWTL {
    
    template <typename T>
    class CompleteWinnerTree : public WinnerTree<T> {
        
    public:
        
        CompleteWinnerTree(T* thePlayer,int numberOfPlayers) {
            tree = NULL;
            initialize(thePlayer,numberOfPlayers);
            
        };
        
        //将一个数组初始化为赢者树
        virtual void initialize (T* thePlayer,int theNumberOfPlayers) override {
            int n = theNumberOfPlayers;
            if (n < 2) {
                //最少要有两个参赛者
                throw IllegalParameterValue("must have at least 2 players");
            }
            
            player = thePlayer;
            numberOfPlayers = n;
            delete [] tree;
            tree = new int [n];
            
            //   s = 2^log (n-1) 最底端最左边的内部节点为s
            int i, s;
            for (s = 1; 2 * s <= n - 1; s += s);
            
            lowExt = 2 * (n - s);
            offset = 2 * s - 1;
            
            //竞赛
            for (i = 2; i <= lowExt; i += 2) {
                play((offset + i) / 2, i - 1, i);
            }
            
            //处理剩余的节点
            if (n % 2 == 1) {
                play(n/2, tree[n - 1], lowExt + 1);
                i = lowExt + 3;
            } else {
                i = lowExt + 2;
            }
            
            for (; i <= n; i += 2) {
                play((i - lowExt + n - 1) / 2, i - 1, i);
            }
        }
        
        //返回锦标赛的胜者的索引
        virtual int winner() const override {
            return tree[1];
        }
        
        
        //在参赛者i改变之后重赛
        virtual void rePlay(int thePlayer) override {
            int n = numberOfPlayers;
            if (thePlayer <= 0 || thePlayer > n) {
                throw IllegalParameterValue("Player index is illegal");
            }
            
            int matchNode,
            leftChild,
            rightChild;
            
          
            if (thePlayer <= lowExt) {
                
                matchNode = (offset + thePlayer) / 2;
                leftChild = 2 * matchNode - offset;
                rightChild = leftChild + 1;
                
            } else {
                
                matchNode = (thePlayer - lowExt + n - 1) / 2;
                
                if (2 * matchNode == n - 1) {
                    leftChild = tree[2 * matchNode];
                    rightChild = thePlayer;
                    
                } else {
                    leftChild = 2 * matchNode - n + 1 + lowExt;
                    rightChild = leftChild + 1;
                }
            }
            
            tree[matchNode] = (player[leftChild] <= player[rightChild]) ? leftChild : rightChild;
            
            if (matchNode == n - 1 && n % 2 == 1) {
                matchNode /= 2;
                tree[matchNode] = (player[tree[n - 1]] <= player[lowExt + 1]) ?
                tree[n - 1] : lowExt + 1;
            }
            
            matchNode /= 2;
            
            for (; matchNode >= 1; matchNode /= 2) {
                tree[matchNode] = (player[tree[2 * matchNode]] <= player[tree[2 * matchNode + 1]]) ?
                tree[2 * matchNode] : tree[2 * matchNode + 1];
            }
        }
        
        
    private:
        
        int lowExt;//最底层外外部节点个数
        int offset;//2^log(n-1) - 1
        int* tree;//表示赢者树（完全二叉树）的数组
        int numberOfPlayers;//参赛者个数
        T* player;//参赛者数组
        
        
        void play(int p,int leftChild,int rightChild) {
            tree[p] = (player[leftChild] <= player[rightChild]) ? leftChild : rightChild;
            
            while (p % 2 == 1 && p > 1) {
                tree[p / 2] = (player[tree[p - 1]] <= player[tree[p]]) ?
                tree[p - 1] : tree[p];
                p /= 2;
            }
        }
        
    };
    
    
}

#endif /* CompleteWinnerTree_hpp */