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  1. // no of ways to divide the given array into 4 equal parts
  2. import java.util.*;
  3. public class Main
  4. {
  5. 	public static void main(String[] args) {
  6. 		Scanner sc = new Scanner(System.in);
  7. 		int n=sc.nextInt();
  8. 		int[]nums = new int[n];
  9.  
  10. 		for(int i= 0;i<n;i++){
  11. 		    nums[i]=sc.nextInt();
  12. 		}
  13. 		int tot_sum=0;
  14. 		for(int i=0;i<n;i++){
  15. 		    tot_sum+=nums[i];
  16. 		}
  17. 		int lhs=0;
  18. 		int rhs=0;
  19. 		int count=0;
  20. 		int count2=0;
  21. 		int count_ans=0;
  22. 		if(tot_sum%4 ==0){
  23. 		    int y=tot_sum/4;
  24.  
  25. 		    //I need current sum 
  26. 		    int current_sum=0;
  27.  
  28. 		    HashMap<Integer,Integer>f = new HashMap<>();
  29. 		    HashMap<Integer,Integer>g = new HashMap<>();
  30.  
  31. 		    int current_sumg=0;
  32.  
  33. 		    for(int j=n-1;j>=0;j--){
  34. 		        current_sumg+=nums[j];
  35. 		        g.put(current_sumg,g.getOrDefault(current_sumg,0)+1);
  36. 		    }
  37.  
  38. 		    for(int j=0;j<n-1;j++){
  39. 		        lhs+=nums[j];
  40. 		        rhs=tot_sum-lhs;
  41. 		        current_sum+=nums[j];
  42.  
  43. 		        g.put(current_sumg,g.get(current_sumg)-1);
  44. 		        if(g.get(current_sumg)==0){
  45. 		          g.remove(current_sumg);   
  46. 		        }
  47.  
  48. 		        current_sumg-=nums[j];
  49.  
  50. 		        if(lhs == 2*y && rhs ==2*y ){
  51. 		          count=count + f.getOrDefault(current_sum/2,0) ;
  52. 		          count2=count2 +g.getOrDefault(current_sumg/2,0);
  53. 		          count_ans +=count*count2;
  54. 		        }
  55. 		        f.put(current_sum,f.getOrDefault(current_sum,0)+1);
  56. 		    }
  57. 		}
  58. 		System.out.print("Number of ways to divide in four equal parts :" + count_ans);
  59. 	}
  60. }
Runtime error #stdin #stdout #stderr 0.13s 17624KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
Exception in thread "main" java.util.NoSuchElementException
	at java.base/java.util.Scanner.throwFor(Scanner.java:937)
	at java.base/java.util.Scanner.next(Scanner.java:1594)
	at java.base/java.util.Scanner.nextInt(Scanner.java:2258)
	at java.base/java.util.Scanner.nextInt(Scanner.java:2212)
	at Main.main(Main.java:7)
https://ideone.com/kvUUzc
language:
Java (HotSpot 12)
created:
1 day ago
visibility:
public

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