1700C - Helping the Nature

subject

Problem - 1700C - Codeforces

The question

​ Give an array , There are three operations ,

• （1） Will be in the array $a_1\sim a_i$ Minus one .
• （2） Will be in the array $a_i\sim a_n$ Minus one .
• （3） Add one to all the numbers in the array .

​ Change all the numbers of the array into 0 Minimum operands of .

Using differential arrays , Convert the original array to all zeros into the difference group to all zeros . You can convert the original operation .

• （1）$b_1-1$,$b_i+1$.
• （2）$b_i-1$.
• （3）$b_1+1$.

therefore , Only operation is found （1） Can divide 1 Add one to other numbers , Only operation （2） Can divide 1 Subtract one from the outside , So you just need to divide the difference group 1 Deal with other places , Last use （2）（3） Operation judgment position 1 Can .

Pay attention to it long long.

#include <iostream>
using namespace std;
typedef long long ll;
const int N=2e5+10;
ll T,a[N],b[N];
void slove(){
    
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1;i<=n;i++)b[i]=a[i]-a[i-1];
	ll ans=0;
	for(int i=2;i<=n;i++){
    
		if(b[i]>0)ans+=b[i];
		else if(b[i]<0){
    
			ans-=b[i];
			b[1]+=b[i];
		}
	}
	cout<<ans+abs(b[1])<<endl;
}
int main(){
    
	cin>>T;while(T--)
	slove();
	return 0;
}