Death to Binary? （模拟）题解

思路：

除去前导0，注意两个1不能相邻（11->100），注意 0 *** 或者*** 0或者0 0情况

用string的reverse（）很舒服

代码：

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<queue>
#include<cmath>
#include<string>
#include<map>
#include<stack>
#include<set>
#include<vector>
#include<iostream>
#include<algorithm>
#define INF 0x3f3f3f3f
#define ll long long
const int N=50;
const int MAX=45;
const int MOD=1000;
using namespace std;
ll fib[N];
void initfib(){
	fib[0]=1;fib[1]=2;
	for(int i=2;i<=MAX;i++){
		fib[i]=fib[i-1]+fib[i-2];
	}
}
void change(ll sum,string &c){
	c.clear();
	int j;
	for(j=MAX;j>=0;j--){
		if(sum>=fib[j]) break;
	}
	for(int i=j;i>=0;i--){
		if(sum>=fib[i]){
			sum-=fib[i];
			c+='1';
		}
		else c+='0';
	}
	if(c.length()==0) c='0';
}
int main(){
	initfib();
	string a,b,c;
	ll A,B,sum;
	while(cin>>a>>b){
		reverse(a.begin(),a.end());
		reverse(b.begin(),b.end());
		A=B=0;
		for(int i=0;i<a.length();i++){
			if(a[i]=='1') A+=fib[i];
		}
		ll cut=0,n;
		n=a.length()-1;
		while(1){
			if(a[n]=='1') break;
			if(a[n]=='0') cut++;
			n--;
		}
		a=a.substr(0,a.length()-cut);	//去掉a前导0
		reverse(a.begin(),a.end());

		for(int i=0;i<b.length();i++){
			if(b[i]=='1') B+=fib[i];
		}
		cut=0;
		n=b.length()-1;
		while(1){
			if(b[n]=='1') break;
			if(b[n]=='0') cut++;
			n--;
		}
		b=b.substr(0,b.length()-cut);	//去掉b前导0
		reverse(b.begin(),b.end());

		sum=A+B;
		change(A,a);
		change(B,b);
		change(sum,c);

		int mxlen=max(a.length(),max(b.length(),c.length()));
		cout<<"  ";
		for(int i=0;i<mxlen-a.length();i++) cout<<" ";
		cout<<a<<endl;
		cout<<"+ ";
		for(int i=0;i<mxlen-b.length();i++) cout<<" ";
		cout<<b<<endl;
		cout<<"  ";
		for(int i=0;i<mxlen;i++) cout<<"-";
		cout<<endl;
		cout<<"  ";
		for(int i=0;i<mxlen-c.length();i++) cout<<" ";
		cout<<c<<endl<<endl;
	}
	return 0;
}