c++ - 如何删除结构 vector 的重复项 C++

Question

我有 vector 运动

 vector<posToMove> movements;

posToMove 是一个结构体:

struct posToMove
{
    int fromX;
    int fromY;
    int toX;
    int toY;
};

我想删除移动中的重复项，我该怎么做？

Answer 1

最简单的方法是使用:

movements.erase(std::unique(movements.begin(), movements.end()), movements.end());

但是std::unique只删除连续 重复的元素，因此您需要对 std::vector 进行排序首先，通过重载 <和 ==运算符(operator):

struct posToMove
{
    int fromX;
    int fromY;
    int toX;
    int toY;

    bool operator < (const posToMove& other) const
    {
        //declare how 2 variable of type posToMove should be compared with <
        return std::make_tuple(fromX, fromY, toX, toY) < std::make_tuple(other.fromX, other.fromY, other.toX, other.toY);
    }

    bool operator == (const posToMove& other) const
    {
        //declare how 2 variable of type posToMove should be compared with ==
        return std::make_tuple(fromX, fromY, toX, toY) == std::make_tuple(other.fromX, other.fromY, other.toX, other.toY);
    }
};

我声明了<和 ==运算符 make_tuple() , 但您也可以将其替换为您选择的比较。

代码:

#include <iostream>
#include <vector>
#include <tuple>
#include <algorithm>
struct posToMove
{
    int fromX;
    int fromY;
    int toX;
    int toY;

    bool operator < (const posToMove& other) const
    {
        //declare how 2 variable of type posToMove should be compared with <
        return std::make_tuple(fromX, fromY, toX, toY) < std::make_tuple(other.fromX, other.fromY, other.toX, other.toY);
    }

    bool operator == (const posToMove& other) const
    {
        //declare how 2 variable of type posToMove should be compared with ==
        return std::make_tuple(fromX, fromY, toX, toY) == std::make_tuple(other.fromX, other.fromY, other.toX, other.toY);
    }
};

std::vector<posToMove>movements;

int main()
{
    movements.push_back({0,1,0,0});
    movements.push_back({1,2,5,7});
    movements.push_back({3,9,9,6});
    movements.push_back({0,1,0,0});
    movements.push_back({4,1,8,0});
    movements.push_back({1,2,5,7});

    std::sort(movements.begin(), movements.end());

    std::cout << "After sort : \n";
    for (auto x : movements)
    {
        std::cout << x.fromX << " " << x.fromY << " " << x.toX << " " << x.toY << "\n";
    }
    std::cout << "\n";

    movements.erase(std::unique(movements.begin(), movements.end()), movements.end());

    std::cout << "After removing : \n";
    for (auto x : movements)
    {
        std::cout << x.fromX << " " << x.fromY << " " << x.toX << " " << x.toY << "\n";
    }
}

结果:

After sort :
0 1 0 0
0 1 0 0
1 2 5 7
1 2 5 7
3 9 9 6
4 1 8 0

After removing :
0 1 0 0
1 2 5 7
3 9 9 6
4 1 8 0

相关:Remove duplicates in vector of structure c++

文档:

• erase() : https://en.cppreference.com/w/cpp/container/vector/erase2

• std::unique : https://en.cppreference.com/w/cpp/algorithm/unique

• std::sort : https://en.cppreference.com/w/cpp/algorithm/sort

• 重载运算符:https://en.cppreference.com/w/cpp/language/operators