Note $$$maxp$$$ as the maximum index of the maximum value in $$$a$$$.
For $$$1 \leq k \leq maxp-1$$$,they do not meet the condition.
For $$$maxp+1 \leq k \leq n$$$,they all meet the condition.
You need to be careful of $$$k==maxp$$$,it meet the condition if and only if there is only one maximum value in $$$a$$$.
Note $$$a_1$$$ as the first $$$\lceil{n/2}\rceil$$$ numbers of $$$a$$$,and $$$a_2$$$ as the last $$$n-\lceil{n/2}\rceil$$$ numbers of $$$a$$$.
Through observation,we found that the following processes will be repeated cyclically:
erase the leftmost number of $$$a_1$$$
erase the leftmost number of $$$a_2$$$
erase the rightmost number of $$$a_1$$$
erase the rightmost number of $$$a_2$$$
In conclusion:
If $$$|a_1|>|a_2|$$$(i.e. $$$n$$$ is odd),the answer is the number in the middle of $$$a_1$$$
If $$$|a_1|=|a_2|$$$(i.e. $$$n$$$ is even),the answer is the number in the middle of $$$a_2$$$
We notice we can convert condition $$$3$$$ to $$$c0(a,l_1,r_1)-c1(a,l_1,r_1)=c1(b,l_2,r_2)-c0(b,l_2,r_2)$$$.
This provides us with convenience: we can independently calculate the left and right value ranges.
If two ranges intersect, the answer is $$$YES$$$,otherwise the answer is $$$NO$$$.
Let's calculate the left value ranges.Make all $$$a_i=0$$$ to $$$1$$$ and $$$a_i=1$$$ to $$$-1$$$,it is the value range of all subarrays of appropriate length.
In fact,we only need to find max subsegment sum and min subsegment sum.It's a classic problem.
You may have already guessed:if $$$x_1<y_1$$$,and you get $$$minsum,maxsum$$$,the range of values is continuous — $$$[minsum,maxsum]$$$.Why?
Consider we have get $$$[L_1,R_1]$$$ which make $$$minsum$$$ and $$$[L_2,R_2]$$$ which make $$$maxsum$$$.
We use continuous transformation to make:$$$[L_1,R_1]->[L_2,R_2]$$$.
Step1:Length Adjustment
For convenience we assume $$$R_1-L_1+1>R_2-L_2+1$$$.
Transform:$$$[L_1,R_1]->[L_1+1,R_1]->[L_1+2,R_1]->...->[L_1',R_1]$$$ $$$(R_1-L_1'+1=R_2-L_2+1)$$$
Step2:"Creeping"
For convenience we assume $$$R_1<R_2$$$.
Transform:$$$[L_1',R_1]->[L_1'+1,R_1]->[L_1'+1,R_1+1]->...->[L_2,R_2]$$$
After once length adjustment and several times creeping,we have transformed $$$[L_1,R_1]$$$ to $$$[L_2,R_2]$$$ continuously and proved the value range is continuous.
You also need to be careful of the edge cases that $$$x_i=y_i(1 \leq i \leq 2)$$$.
We notice we can calculate each bit independently.
In other words,note $$$f(a_i,j)$$$ as the $$$j^{th}$$$ bit under the binary representation of $$$a_i$$$,the answer is $$$\Sigma_{i=0}^{i=30} 2^{i}*(\Sigma f(a_l,i)⊕...⊕f(a_r,i))$$$.
Let's calculate the sum of the $$$0^{th}$$$ bit.
$$$a_{i,0}=0,1,0,1,...$$$
Note $$$pre_{i,0}=a_{1,0}⊕...⊕a_{i,0}$$$,then
$$$pre_{i,0}=0,1,1,0,0,1,1,0,...$$$
We noticed that the loop section of this sequence is $$$4$$$ and can calculate the total number of $$$'1'$$$(note it as $$$c_1$$$).The total number of subarrays with xor-value $$$1$$$ is $$$c_1*(n+1-c_1)$$$.
For the $$$1,2,...30^{th}$$$ bit,use the similar method to calculate it.
Consider an easier problem:for a fixed score $$$x_1*x_2*...*x_k$$$($$$x_i$$$ is one of the prefix minimum value),how to calculate the number of schemes?
Consider such a sequence construction process: put all $$$0$$$'s, all $$$1$$$'s, and all $$$2$$$'s,...
If you want the prefix minimum value of $$$i$$$ to appear in $$$a$$$, what should you do?We can get:at least one $$$i$$$ must be placed at the head of the current sequence.
This is actually equivalent to the classical problem: $$$m_i$$$ balls are put into $$$(m_1+...+m_{i-1}+1)$$$ boxes, the first box must have at least one ball,count the number of schemes.
The answer is:
$$$U_i=C(m_i-1+(m_1+...+m_{i-1}),(m_1+...+m_{i-1}))$$$.
If you want the prefix minimum value of i not to appear in $$$a$$$, what should you do?We can get:no $$$i$$$ must be placed at the head of the sequence.Solve it in a similar way as above.
The answer is:
$$$V_i=C(m_i+(m_1+...+m_{i-1})-1,(m_1+...+m_{i-1})-1)$$$.
Let's go back to the easier problem.The number of schemes is $$$\Phi_{i∈X}U_i * \Phi_{i∉X}V_i$$$.
If you know the pre-min set S of A, how to find the number of schemes?For example,N=5,S={1,3,5},the number is:U[1]*V[2]*U[3]*V[4]*U[5].
Finally, how to calculate the total score?With some tricks, we can convert the formula into:(1*U[1]+V[1])(2*U[2]+V[2])...(N*U[N]+V[N]).
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