#include <iostream>
#include <cstdio>
using namespace std;

typedef long long LL;
LL t;
int hour,mint,sec;

int main(){
	
	cin>>t;
	t /= 1000;
	LL oneday = 60*60*24;
	t %= oneday;
	hour = t/(60*60);
	mint = (t/60)%(60);
	sec = (t-60*60*hour-60*mint);
	printf("%02d:%02d:%02d",hour,mint,sec) ;
	
	
	
	
	return 0;
}

打卡

#include <bits/stdc++.h>
using namespace std;
#define ll unsigned long long
int main(){
	ll n;
	cin>>n;
	n/=1000;
	ll k=n/3600; 
	ll H=k%24;
	n-=k*3600;
	ll m=n/60;
	n-=m*60;
	if(H<=9) cout<<"0"<<H<<":";
	else cout<<H<<":";
	if(m<=9) cout<<"0"<<m<<":";
	else cout<<m<<":";
	if(n<=9) cout<<"0"<<n;
	else cout<<n;
	return 0;
} 

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int main()
{
	ll time,h,m,s;
	scanf("%lld",&time);
	time/=1000;
	s=time%60;
	time/=60;
	m=time%60;
	time/=60;
	h=time%24;
	printf("%02lld:%02lld:%02lld\n",h,m,s);
	return 0;
}

题目来源

2021年蓝桥杯省赛第一场F题

题目链接：http://acm.mangata.ltd/p/P1488

考点

暴力、小技巧

视频讲解

视频连接：https://www.bilibili.com/video/BV1z44y1s7wD/

思路

因为给出的是一个毫秒值，那么我们要将其转化为秒、分钟、小时，注意的是1s=1000ms，其余的进制都是60，别记错了！，关于补0显示：%02d这样的话如果不满两位数，会自动补上的

代码

#include<bits/stdc++.h>
using namespace std;
//----------------自定义部分----------------
#define ll long long
#define mod 1000000009
#define endl "\n"
#define PII pair<int,int>

int dx[4]={0,-1,0,1},dy[4]={-1,0,1,0};

ll ksm(ll a,ll b) {
	ll ans = 1;
	for(;b;b>>=1LL) {
		if(b & 1) ans = ans * a % mod;
		a = a * a % mod;
	}
	return ans;
}

ll lowbit(ll x){return -x & x;}

const int N = 2e6+10;
//----------------自定义部分----------------
int n,m,q,a[N];

int main()
{
//	std::ios::sync_with_stdio(false);
//	std::cin.tie(nullptr);
//	std::cout.tie(nullptr);
	ll tm;
	scanf("%lld",&tm);
	tm /= 1000;
	ll s = tm;
	s %= 60;
	tm /= 60;
	ll m = tm;
	m %= 60;
	tm /= 60;
	ll h = tm;
	h %= 24;
	printf("%02lld:%02lld:%02lld\n",h,m,s);
	return 0;
}