排序然后搜索（向量c ++）

Question

我已经尝试过单独使用向量而不是固定内存数组进行搜索，并且效果非常好。但是现在当我尝试首先对向量进行排序 以使其能够在二分搜索中工作 时，程序在用户输入向量列表后停止 这是代码

#include <iostream>
#include <vector>
using namespace std;
void BubbleSort(vector<int>list){
    int temp;
    for (int i=0;i<list.size();i++){
        for (int j=1;j<list.size();j++){
            if(list[i]>list[j]){
                list[i]=temp;
                list[j]=list[i];
                temp=list[j];
            }
        }
    }
}
int Binary_search(vector<int>list,int target){
    int maximum=(list.size())-1;
    int minimum = 0;
    int mean;
    while (maximum>minimum){
        mean = (maximum+minimum)/2;
        if (list[mean] == target){
            cout << "The number you're looking for is found! \n";
            return mean;
        }
        else if(list[mean] > target){
            maximum = mean;
        }
        else{
            minimum = mean;
        }
    }
    return -1;
}
int main()
{
    unsigned int k;
    int x,a,target;
    vector<int>list;
    cout << "Enter the amount of numbers you want to enlist \n";
    cin >> k;
    while((list.size()< k) && (cin >> x)){
        list.push_back(a);
    }
    BubbleSort(list);
    cout << "Enter the target that you want to search for \n";
    cin >> target;
    int result = Binary_search(list,target);
    if(result == -1){
        cout << "Your result is not found ";
    }
    else{
        cout << "Your result is found at the index: " << result;
    }
    return 0;
}

我希望程序进行排序（但不是打印出向量 sorted ，只是从后面排序，然后在搜索后显示结果） 问题肯定出在排序部分，但我不知道在它之前使用冒泡排序是否可以，谁能指出我正确的排序方式然后搜索？

Answer 1

@Oliver_Queen 你的代码有一些问题，但如果你遵循@1201ProgramAlarm 和@Blastfurnace 的cmets，你可以解决部分问题，但在Binary_search() 函数中你应该使用mean-1 或mean+1分别为 maximum 和 minimum 并检查最后是否为真条件，这里是你的代码修复：

void BubbleSort(vector<int> &list){
    int temp;
    for (int i=0;i<list.size();i++){
        for (int j=i+1;j<list.size();j++){
            if(list[i]>list[j]){
                temp=list[i];
                list[i]=list[j];
                list[j]=temp;
            }
        }
    }
}

在函数Binary_search() 中喜欢：

int Binary_search(vector<int>list,int target){
    int maximum=(list.size())-1;
    int minimum = 0;
    int mean;
    while (maximum>minimum){
        mean = (maximum+minimum)/2;
        if (list[mean] == target){
            cout << "The number you're looking for is found! \n";
            return mean;
        }
        else if(list[mean] > target){
            maximum = mean-1;
        }
        else{
            minimum = mean+1;
        }
    }
    if (list[minimum] == target) return minimum;
    return -1;
}

或者为了避免 ciclo while 之后的条件：

int Binary_search(vector<int>list,int target){
    int maximum=(list.size())-1, minimum = 0, mean;
    while (minimum <= maximum){
        mean = (maximum+minimum)/2;
        if (list[mean] == target)    return mean;
        else if(list[mean] > target) maximum = mean-1;
        else                         minimum = mean+1;
    }
    return -1;
}

但我的建议是您使用算法库中的std::sort() 来执行O(N*log(N)) 中的排序，其中N 是要排序的项目数，并使用std::binary_search 检查它是否属于或std::lower_bound找到不小于给定值的第一项。

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
    unsigned int k;
    int x,a,target;
    vector<int>list;
    cout << "Enter the amount of numbers you want to enlist \n";
    cin >> k;
    while((list.size()< k) && (cin >> x)){
        list.push_back(x);
    }
    sort(list.begin(), list.end());
    cout << "Enter the target that you want to search for \n";
    cin >> target;
    auto result = lower_bound(list.begin(), list.end(), target);
    if(result == list.end()){
        cout << "Your result is not found ";
    }
    else{
        cout << "Your result is found at the index: " << result-list.begin();
    }
    return 0;
}