Problem: 2060D - Subtract Min Sort
Language: java

Solution 1 (runtime: 655 ms):
import java.util.*;
import java.lang.*;
import java.math.BigInteger;
import java.io.*;
public class cf{
    // public static long gcd(long a,long b){
    //     while(a!=0 && b!=0){
    //         if(a<b){
    //             b=b%a;
    //         }else{
    //             a=a%b;
    //         }
    //     }
    //     if(a!=0){
    //         return a;
    //     }else{
    //         return b;
    //     }
    // }  
    // public static long lcm(long a,long b){
    //     return (a/gcd(a,b))*b;
    // }

    public static void main(String args[]){
        Scanner sc=new Scanner(System.in);
        int tsts=sc.nextInt();
        for(int t=0;t<tsts;t++){
            int n=sc.nextInt();
            // int k=sc.nextInt();
            // int a4=sc.nextInt();
            // int a5=sc.nextInt();
            // int r2=sc.nextInt();
            // StringBuilder s=new StringBuilder(sc.next());
            // String a=sc.next();
            // String b=sc.next();
            // String c=sc.next();
            int[] a=new int[n];
            for(int i=0;i<n;i++){
                a[i]=sc.nextInt();
            }
            // int[] b=new int[n];
            // for(int i=0;i<n;i++){
            //     b[i]=sc.nextInt();
            // }
            // long n=sc.nextLong();
            // long k=sc.nextLong();
            // long r=sc.nextInt();
            // long c=sc.nextInt();
            for(int i=0;i<n-1;i++){
                int temp=Math.min(a[i],a[i+1]);
                a[i]-=temp;
                a[i+1]-=temp;
            }
            int[] b=new int[n];
            for(int i=0;i<n;i++){
                b[i]=a[i];
            }
            Arrays.sort(b);
            boolean flag=true;
            for(int i=0;i<n;i++){
                if(a[i]!=b[i]){
                    flag=false;
                    break;
                }
            }
            if(flag) System.out.println("Yes");
            else System.out.println("No");
        }    
    }
}

Solution 2 (runtime: 312 ms):
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class prob {

    static class FastReader {
        BufferedReader b;
        StringTokenizer s;

        public FastReader() {
            b = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (s == null || !s.hasMoreElements()) {
                try {
                    s = new StringTokenizer(b.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return s.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        float nextFloat() {
            return Float.parseFloat(next());
        }

        boolean nextBoolean() {
            return Boolean.parseBoolean(next());
        }

        // Method to read the next line as a string
        String nextLine() {
            String str = "";
            try {
                if (s == null || !s.hasMoreTokens()) {
                    str = b.readLine();
                } else {
                    str = s.nextToken("\n");
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }

    //===================================================================================================

    public static void main(String[] args) {
        FastReader fastReader = new FastReader();

        int t=0;
        t = fastReader.nextInt();

        while(t-- >0){
            int n = fastReader.nextInt();
            int[] arr = new int[n];

            for(int i=0;i<n;i++){
                arr[i] = fastReader.nextInt();
            }

            solve(arr, n);
        }
    }

    public static void solve(int[] arr, int n){

        for(int i=0;i<n-1;i++){
            int var = Math.min(arr[i], arr[i+1]);
            arr[i]-=var;
            arr[i+1]-=var;
        }

        for(int i=0;i<n-1;i++){
            if(arr[i+1]<arr[i]){
                System.out.println("NO");
                return;
            }
        }

        System.out.println("YES");
    }
}