蓝桥杯备战9.拼数

P1012 [NOIP1998 提高组] 拼数 - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

这道题作对了，但是题解看到更好的

我写的史

#include<bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
const int N = 2e7+10,M = 1e3+10;
int a[N],h[N];
struct birthday
{
	string name;
	int y,m,d,id;	
};

bool cmp(int a,int b)
{
	string s1 = to_string(a);
	string s2 = to_string(b);
	int m = min(s1.size(),s2.size());
	for(int i=0;i<m;i++)
	{
		if(s1[i]>s2[i])
		{
			return 1;
		}
		else if(s1[i]<s2[i])return 0;
	}
	if(s1.size()>s2.size())
	{
		if(s1[m]>s2[m-1])return 1;
		else return 0;
	}
	else
	{
		//s2>s1
		if(s1[m-1]>s2[m])return 1;
		else return 0;
	}
}
signed main()
{
	std::ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int n;cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	sort(a+1,a+1+n,cmp);
	for(int i=1;i<=n;i++)
	{
		cout<<a[i];
	}
	return 0;
}

cmp函数优化之后

#include<bits/stdc++.h>
#define endl '\n'
#define int long long
using namespace std;
const int N = 2e7+10,M = 1e3+10;
int a[N],h[N];
struct birthday
{
	string name;
	int y,m,d,id;	
};

bool cmp(int a,int b)
{
	string s1 = to_string(a);
	string s2 = to_string(b);
	return (s1+s2>s2+s1);
}
signed main()
{
	std::ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	int n;cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	sort(a+1,a+1+n,cmp);
	for(int i=1;i<=n;i++)
	{
		cout<<a[i];
	}
	return 0;
}