Submission #2412905

---

Source Code Expand

#include<bits/stdc++.h>
#define MN 300000
#define mod 1000000007
char s[MN+5];
int p[MN+5],f[MN+5][3][3];
inline void rw(int&a,int b){if((a+=b)>=mod)a-=mod;}
int main(){
	int n,i,j,k,ans=0;
	scanf("%s",s+1);n=strlen(s+1);
	for(p[n+1]=1,i=n;i;--i)p[i]=(p[i+1]<<(s[i]=='?'))%mod;
	for(f[0][0][0]=i=1;i<=n;++i)for(j=0;j<3;++j)for(k=0;k<3;++k){
		if(s[i]!='0')
			if(k)rw(f[i][j][k-1],f[i-1][j][k]);
			else if(j<2)rw(f[i][j+1][k],f[i-1][j][k]);
			else rw(ans,1LL*f[i-1][j][k]*p[i+1]%mod);
		if(s[i]!='1')rw(f[i][j][k<2?k+1:1],f[i-1][j][k]);
	}
	rw(ans,f[n][1][0]);
	rw(ans,f[n][2][1]);
	printf("%d",ans);
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:9:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s",s+1);n=strlen(s+1);
                 ^

Judge Result