c++解数学题

1，鸡兔同笼

#include <bits/stdc++.h>
using namespace std;
int main(){
	int a,b,ji,tu;
	cin >> a >> b;
	ji = a;
	tu = 0;
	while ( ji*2+tu*4!=b ){
		ji--;
		tu++;
	}
	cout << ji << " " <<tu;
}

2，调和级数

#include <bits/stdc++.h>
using namespace std;
int main()
{
	unsigned long long n,m;
	double sum=0;
	cin>>m;
	
	for(n=0;sum<m;)
    {
	    n++;
	    sum=sum+(1.0/n);
	    if(n>1000000){cout<<"too large";return 0;}	    
    }
    cout<<n;
}

3，附上一个简易计算器

#include <bits/stdc++.h>
#define int long long
using namespace std; 
signed main(){
	unsigned int a,c;
	char b;
	cin>>a>>b>>c;
	if(b=='+')cout<<a<<"+"<<c<<"="<<a+c;
	else if(b=='-')cout<<a<<"-"<<c<<"="<<a-c;
	else if(b=='*')cout<<a<<"*"<<c<<"="<<a*c;
	else if(b=='/')cout<<a<<"/"<<c<<"="<<a/c;
}