Submission #18167089

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Source Code Expand

/*
after dusk passed,
there is a starry sky.
*/
#include <bits/stdc++.h>
#define inf 0x3f3f3f3f
#define m_k make_pair
using namespace std;
const int N=1e5+100;
int a,b,n,ans[N];
char c[20];
stack <int> s;
inline int read()
{
	int f=1,x=0;char s=getchar();
	while(s<'0'||s>'9'){if(s=='-')f=-1;s=getchar();}
	while(s>='0'&&s<='9'){x=x*10+s-'0';s=getchar();}
	return x*f;
}
inline bool query(int x,int y)
{
	printf("? %d %d\n",x,y);
	fflush(stdout);
	scanf("%s",c);
	if (c[0]=='Y') return 1;
	else return 0;
}
signed main()
{
	a=read();b=read();n=a+b;
	if (a<=b)
	{
		printf("Impossible\n");
		return 0;
	}
	for (int i=0;i<n;i++)
	{
		if (s.empty()){s.push(i);continue;}
		if (query(s.top(),i)) s.push(i);
		else s.pop();
	}
	int x=s.top();
	for (int i=0;i<n;i++) ans[i]=query(x,i);
	printf("! ");
	for (int i=0;i<n;i++) printf("%d",ans[i]);
	printf("\n");
}

Submission Info

Compile Error

./Main.cpp: In function ‘bool query(int, int)’:
./Main.cpp:24:7: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   24 |  scanf("%s",c);
      |  ~~~~~^~~~~~~~

Judge Result