class Ruler
{
/*public static boolean f(int[] a){
int l=a.length,i=0,b=0,e=l-1;
int[] x=new int[l];
for(;i<l;i++)x[i]=i;
for(i--;i>0;i--)
if(a[i]==x[b]) b++;
else if(a[i]==x[e]) e--;
else return false;
return true;
}*/
public static
boolean f(int[]a){int l=a.length,i=0,b=0,e=l-1;int[]x=new int[l];for(;i<l;i++)x[i]=i;for(i--;i>0;i--)if(a[i]==x[b])b++;else if(a[i]==x[e])e--;else return 0>1;return 1>0;}
{
int[] antsy={4, 3, 5, 2, 1, 0};
int[] notAntsy={3, 2, 5, 4, 1, 0};
System.
out.
println(f
(notAntsy
)); int[] antsy2={6, 5, 4, 7, 3, 8, 9, 2, 1, 0};
System.
out.
println(f
(antsy2
)); int[] notAntsy2={4, 3, 5, 6, 7, 2, 9, 1, 0, 8};
System.
out.
println(f
(notAntsy2
)); }
}
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