private static int sumArrMaxDivide(int[] num, int start, int mid, int end) { //找出跨越中间点的最大子数组 int startSum = Integer.MIN_VALUE; int sum = 0; for (int i = mid; i >= start; i--) { sum += num[i]; startSum = Math.max(startSum, sum); } int endSum = Integer.MIN_VALUE; sum = 0; for (int i = mid + 1; i <= end; i++) { sum += num[i]; endSum = Math.max(endSum, sum); } return Math.max(startSum, 0) + Math.max(endSum, 0); }//将这里的for循环换成while循环

可以将这里的 for 循环换成 while 循环，代码如下：

private static int sumArrMaxDivide(int[] num, int start, int mid, int end) {
//找出跨越中间点的最大子数组
int startSum = Integer.MIN_VALUE;
int sum = 0;
int i = mid;
while (i >= start) {
sum += num[i];
startSum = Math.max(startSum, sum);
i--;
}
int endSum = Integer.MIN_VALUE;
sum = 0;
i = mid + 1;
while (i <= end) {
sum += num[i];
endSum = Math.max(endSum, sum);
i++;
}
return Math.max(startSum, 0) + Math.max(endSum, 0);
}

相关问题

请帮我设计一个C++程序，该程序的功能是有关各种搜索树效率比较，使用BST、AVL、B+树进行比较，要求拥有数组作为存储模块存储数据，时间模块进行计算各搜索树的时间，随机数生成模块进行随机数的生成并且传输给各搜索树进行计算，最后设计一个输出模块要求给出计算后的时间比较

好的，我可以帮你设计一个C++程序，该程序可以比较BST、AVL、B+树的效率，并输出它们的时间比较结果。下面是程序的基本框架：

#include <iostream>
#include <ctime>
#include <cstdlib>
#include <chrono>
#include <vector>
#include "bst.h" // 包含BST的头文件
#include "avl.h" // 包含AVL的头文件
#include "bptree.h" // 包含B+树的头文件

using namespace std;

int main() {
    int n; // 数据量
    cout << "请输入数据量n：";
    cin >> n;

    // 随机生成n个数据
    vector<int> data(n);
    srand(time(0));
    for (int i = 0; i < n; i++) {
        data[i] = rand();
    }

    // BST
    BST bst;
    auto start = chrono::steady_clock::now();
    for (int i = 0; i < n; i++) {
        bst.insert(data[i]);
    }
    auto end = chrono::steady_clock::now();
    chrono::duration<double> elapsed_seconds = end - start;
    cout << "BST插入" << n << "个数据所需时间：" << elapsed_seconds.count() << "秒" << endl;

    // AVL
    AVL avl;
    start = chrono::steady_clock::now();
    for (int i = 0; i < n; i++) {
        avl.insert(data[i]);
    }
    end = chrono::steady_clock::now();
    elapsed_seconds = end - start;
    cout << "AVL插入" << n << "个数据所需时间：" << elapsed_seconds.count() << "秒" << endl;

    // B+树
    BPTree bptree;
    start = chrono::steady_clock::now();
    for (int i = 0; i < n; i++) {
        bptree.insert(data[i]);
    }
    end = chrono::steady_clock::now();
    elapsed_seconds = end - start;
    cout << "B+树插入" << n << "个数据所需时间：" << elapsed_seconds.count() << "秒" << endl;

    return 0;
}

在这个程序中，我们使用了 `chrono` 库来计算各搜索树的时间，使用了 `vector` 存储随机生成的数据。同时，我们还需要实现BST、AVL和B+树的代码，可以参考以下代码：

// BST
struct TreeNode {
    int val;
    TreeNode* left;
    TreeNode* right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

class BST {
public:
    BST() {
        root = NULL;
    }

    void insert(int val) {
        if (root == NULL) {
            root = new TreeNode(val);
            return;
        }
        TreeNode* cur = root;
        while (cur != NULL) {
            if (val < cur->val) {
                if (cur->left == NULL) {
                    cur->left = new TreeNode(val);
                    return;
                } else {
                    cur = cur->left;
                }
            } else {
                if (cur->right == NULL) {
                    cur->right = new TreeNode(val);
                    return;
                } else {
                    cur = cur->right;
                }
            }
        }
    }

private:
    TreeNode* root;
};

// AVL
class AVL {
public:
    AVL() {
        root = NULL;
    }

    void insert(int val) {
        root = insertHelper(root, val);
    }

private:
    struct TreeNode {
        int val;
        int height;
        TreeNode* left;
        TreeNode* right;
        TreeNode(int x) : val(x), height(1), left(NULL), right(NULL) {}
    };

    int getHeight(TreeNode* node) {
        if (node == NULL) {
            return 0;
        }
        return node->height;
    }

    int getBalanceFactor(TreeNode* node) {
        if (node == NULL) {
            return 0;
        }
        return getHeight(node->left) - getHeight(node->right);
    }

    TreeNode* leftRotate(TreeNode* node) {
        TreeNode* right = node->right;
        TreeNode* left = right->left;
        right->left = node;
        node->right = left;
        node->height = max(getHeight(node->left), getHeight(node->right)) + 1;
        right->height = max(getHeight(right->left), getHeight(right->right)) + 1;
        return right;
    }

    TreeNode* rightRotate(TreeNode* node) {
        TreeNode* left = node->left;
        TreeNode* right = left->right;
        left->right = node;
        node->left = right;
        node->height = max(getHeight(node->left), getHeight(node->right)) + 1;
        left->height = max(getHeight(left->left), getHeight(left->right)) + 1;
        return left;
    }

    TreeNode* insertHelper(TreeNode* node, int val) {
        if (node == NULL) {
            return new TreeNode(val);
        }
        if (val < node->val) {
            node->left = insertHelper(node->left, val);
        } else {
            node->right = insertHelper(node->right, val);
        }
        node->height = max(getHeight(node->left), getHeight(node->right)) + 1;
        int balanceFactor = getBalanceFactor(node);
        if (balanceFactor > 1 && getBalanceFactor(node->left) >= 0) {
            return rightRotate(node);
        }
        if (balanceFactor > 1 && getBalanceFactor(node->left) < 0) {
            node->left = leftRotate(node->left);
            return rightRotate(node);
        }
        if (balanceFactor < -1 && getBalanceFactor(node->right) <= 0) {
            return leftRotate(node);
        }
        if (balanceFactor < -1 && getBalanceFactor(node->right) > 0) {
            node->right = rightRotate(node->right);
            return leftRotate(node);
        }
        return node;
    }

    TreeNode* root;
};

// B+树
class BPTree {
public:
    BPTree() {
        // 初始化根节点
        root = new BPNode();
        root->isLeaf = true;
        root->keyNum = 0;
    }

    void insert(int val) {
        BPNode* curNode = root;
        // 找到插入的叶子节点
        while (!curNode->isLeaf) {
            int i = 0;
            while (i < curNode->keyNum && curNode->keys[i] <= val) {
                i++;
            }
            curNode = curNode->children[i];
        }
        // 插入到叶子节点中
        insertToNode(curNode, val);
        // 调整B+树
        while (curNode != root && curNode->keyNum == MAX_KEY_NUM) {
            BPNode* parent = curNode->parent;
            BPNode* newNode = splitNode(curNode);
            insertToNode(parent, newNode->keys[0]);
            newNode->parent = parent;
            curNode = parent;
        }
        if (curNode == root && curNode->keyNum == MAX_KEY_NUM) {
            BPNode* newNode = splitNode(curNode);
            BPNode* newRoot = new BPNode();
            newRoot->keys[0] = newNode->keys[0];
            newRoot->children[0] = curNode;
            newRoot->children[1] = newNode;
            newRoot->keyNum = 1;
            curNode->parent = newRoot;
            newNode->parent = newRoot;
            root = newRoot;
        }
    }

private:
    static const int MAX_KEY_NUM = 4; // 每个节点最多存储的关键字数
    static const int MIN_KEY_NUM = MAX_KEY_NUM / 2; // 每个节点最少存储的关键字数
    static const int MAX_CHILD_NUM = MAX_KEY_NUM + 1; // 每个节点最多的孩子数

    struct BPNode {
        int keys[MAX_KEY_NUM];
        BPNode* children[MAX_CHILD_NUM];
        BPNode* parent;
        int keyNum;
        bool isLeaf;
        BPNode() : keyNum(0), isLeaf(false) {}
    };

    void insertToNode(BPNode* node, int val) {
        int i = node->keyNum - 1;
        while (i >= 0 && node->keys[i] > val) {
            node->keys[i + 1] = node->keys[i];
            i--;
        }
        node->keys[i + 1] = val;
        node->keyNum++;
    }

    BPNode* splitNode(BPNode* node) {
        BPNode* newNode = new BPNode();
        newNode->isLeaf = node->isLeaf;
        int mid = node->keyNum / 2;
        for (int i = mid + 1; i < node->keyNum; i++) {
            newNode->keys[i - mid - 1] = node->keys[i];
            newNode->children[i - mid - 1] = node->children[i];
            if (node->children[i] != NULL) {
                node->children[i]->parent = newNode;
            }
        }
        newNode->children[node->keyNum - mid - 1] = node->children[node->keyNum];
        if (node->children[node->keyNum] != NULL) {
            node->children[node->keyNum]->parent = newNode;
        }
        node->keyNum = mid;
        newNode->keyNum = node->keyNum;
        if (node->parent != NULL) {
            int i = node->parent->keyNum - 1;
            while (i >= 0 && node->parent->children[i] != node) {
                i--;
            }
            insertToNode(node->parent, node->keys[mid]);
            node->parent->children[i + 1] = newNode;
        }
        return newNode;
    }

    BPNode* root;
};

在这个程序中，我们实现了BST、AVL和B+树的代码，其中B+树的实现比较复杂，需要注意。另外，代码中的 `bst.h`、`avl.h` 和 `bptree.h` 分别是BST、AVL和B+树的头文件，需要根据实际情况进行修改。

最后，运行程序，输入数据量n，程序会自动随机生成n个数据，然后分别计算BST、AVL和B+树的插入时间，并输出时间比较结果。你可以根据需要对代码进行修改和扩展，以满足更多的需求。