MergeSort-vector

归并排序-vector实现

#include <iostream>
#include <vector>
using std::cout;
using std::endl;
using std::vector;

void Merge(vector<int> &v, int L, int M, int R)
{
    //拆分成两个vector:left和right
    //vector(begin,end):复制[begin,end)区间内另一个数组的元素到vector中
    vector<int> left(v.begin() + L, v.begin() + M + 1);
    vector<int> right(v.begin() + M + 1, v.begin() + R + 1);
    //两个迭代器
    auto left_it = left.cbegin();
    auto right_it = right.cbegin();
    int i = L;
    //合并vector
    while (left_it != left.cend() && right_it != right.cend())
    {
        if (*left_it < *right_it)
            v[i++] = *(left_it++);
        else
            v[i++] = *(right_it++);
    }
    while (left_it != left.cend())
        v[i++] = *(left_it++);
    while (right_it != right.cend())
        v[i++] = *(right_it++);
}
//Ascending
void MergeSort(vector<int> &v, int L, int R)
{
    if (L == R)
        return;
    else
    {
        MergeSort(v, L, (L + R) / 2);
        MergeSort(v, (L + R) / 2 + 1, R);
        Merge(v, L, (L + R) / 2, R);
    }
}
int main(void)
{
    vector<int> v = {4, 3, 2, 1, 0};
    MergeSort(v, 0, 4);
    for (int i = 0; i < 5; i++)
        cout << v[i] << endl;
    return 0;
}