next permutation

The next permutation refers to the lexicographically next greater arrangement of a given sequence of numbers. To find the next permutation, you can follow these steps:

1. Start from the rightmost position of the sequence and move left until you find a pair of adjacent elements (i, i+1) where i is the index.
2. Now, find the rightmost element to the right of i that is greater than the element at index i.
3. Swap the elements at indices i and j.
4. Reverse the subarray to the right of index i.
5. The resulting arrangement will be the next permutation.

If there is no next permutation possible, then reverse the entire sequence to get the lexicographically smallest arrangement.

相关问题

nextpermutation

next_permutation是一个STL函数，用于计算给定范围内的下一个排列。它的函数原型为：bool next_permutation(iterator start, iterator end)。该函数可以用来生成给定序列的下一个排列。例如，对于序列{a, b, c}，next_permutation会生成下一个排列{a, c, b}。在函数的调用过程中，它会对给定范围内的元素进行全排列，并且改变这些元素的顺序。所以，如果你想要生成给定序列的所有可能排列，可以反复调用next_permutation直到返回false为止。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
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nextpermutation函数

next_permutation函数是一个C++标准库中的函数，用于生成给定序列的下一个排列。它会将当前序列重新排列为下一个字典序更大的排列。如果不存在下一个更大的排列，则会将序列重新排列为最小的字典序排列。

该函数的使用需要包含<algorithm>头文件。下面是next_permutation函数的使用示例：

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

int main() {
    std::vector<int> nums = {1, 2, 3};

    // 获取下一个排列
    while (std::next_permutation(nums.begin(), nums.end())) {
        for (int num : nums) {
            std::cout << num << " ";
        }
        std::cout << std::endl;
    }

    return 0;
}

上述示例中，初始序列为{1, 2, 3}，通过循环调用next_permutation函数，可以依次获取到该序列的所有排列。输出结果如下：

1 3 2 
2 1 3 
2 3 1 
3 1 2 
3 2 1