April challenge upsolving

test.cpp

--- first question :
conider the criteria of minimum surface area, for that all the cubes must be placed adjacent with side.
with number of faces visible, allot the maximum possible number to them

void solve(){
	int n; cin>>n;
	int four=n/4;
	int rem=n%4;
	int ans=four*44;
	if(four!=0){
		if(rem==0){
			ans+=4*4;
		}else if(rem==1){
			ans+=3*4;
			ans+=20;
		}else if(rem==2){
			ans+=2*4;
			ans+=36;
		}else{
			ans+=4;
			ans+=51;
		}
	}else{
		if(rem==0){
			ans+=0;
		}else if(rem==1){
			ans+=20;
		}else if(rem==2){
			ans+=36;
		}else{
			ans+=51;
		}
	}
	cout<<ans<<endl;
}




--- second question :
The array is kind of non decreasing in nature. Hence for each index as starting point, find the shortest length square that has the sum 
better than required and rest of them will include in ans. Use binary search for this. for calculating sum use prefix sums.
 
void solve(){
	int n,m,k; cin>>n>>m>>k;
	int a[n+1][m+1]; f(i,0,n+1) f(j,0,m+1) a[i][j]=0;
	f(i,1,n+1) f(j,1,m+1) cin>>a[i][j];
	int pre[n+1][m+1]; f(i,0,n+1) f(j,0,m+1) pre[i][j]=0;
	f(i,1,n+1) 
		f(j,1,m+1) pre[i][j]+=pre[i][j-1]+a[i][j];
	f(j,1,m+1)
		f(i,1,n+1) pre[i][j]+=pre[i-1][j];
	int cnt=0;
	f(i,1,n+1) f(j,1,m+1) {
		int low=0,high=min(n-i,m-j),poss=-1;
		while(low<=high){
			int mid=low+high; mid/=2;
			int sum_in_range=pre[i+mid][j+mid]-pre[i-1][j+mid]-pre[i+mid][j-1]+pre[i-1][j-1];
			if(sum_in_range >= k*(mid+1)*(mid+1)) {
				poss=mid;
				high=mid-1;
			}else low=mid+1;
		}
		if(poss!=-1)
			cnt+=min(n-i,m-j)-poss+1;
	}
	cout<<cnt<<endl;
}