to_string()

字符数组

注意结尾的 '\n'

#include<iostream>
#include<string>

using namespace std;

const int  N =  100;
char s[N];
char ss[N];

string to_String(int n)
{
    int i = 0 ,j = 0;
    if (n < 0)// 处理负数
    {
        n = 0 - n;
        j = 1;
        ss[0] = '-';
    }

    while (n > 0)
    {
        s[i ++] = n % 10 + '0';
        n /= 10;
    }

    s[i] = '\0'; // 结尾 
    // 逆序过来 
    i = i - 1;
    while (i >= 0)
    {
        ss[j++] = s[i--];
    }
    ss[j] = '\0';
    return ss;
}

int main()
{
    cout << "请输入整数:";
    int m;
    cin >> m;
    string s = "转为字符串：" + to_String(m)  ;
    cout << s << endl;
    system("pause");
    return 0;
}

字符串

借助reverse

#include<iostream>
#include<string>
#include <algorithm>

using namespace std;


string to_String(int n)
{
    string s = "";
    int i = 0 ,j = 0;
    if (n < 0)// 处理负数
    {
        n = 0 - n;
        j = 1;
        s += '-';
    }

    while (n > 0)
    {
        s += n % 10 + '0';
        n /= 10;
    }

    reverse(s.begin() + j, s.end()); 

    return s;
}

int main()
{
    cout << "请输入整数:";
    int m;
    cin >> m;
    string s = "转为字符串：" + to_String(m)  ;
    cout << s << endl;
    system("pause");
    return 0;
}

nnext_permutation

void nextPermutation(vector<int>& nums) {
    int n = nums.size();

    int k = n - 1;
    while(k > 0 && nums[k - 1] >= nums[k]) k --;

    if(k <= 0) reverse(nums.begin(), nums.end());  // 没有升序 
    else
    {
        int t = k;  // 找最大的最小的那个交换
        while(t + 1 < n && nums[t + 1] > nums[k - 1]) t ++;
        swap(nums[k - 1], nums[t]);
        reverse(nums.begin() + k, nums.end()); // 从下边为k的地方翻转
    }
}