927. Three Equal Parts

class Solution {
    public int[] threeEqualParts(int[] arr) {
        int n = arr.length;
        int oneCount = 0; 
        
        //Counting total number of 1's
        for(int i : arr) if(i==1) oneCount++;
        
        //Base exit condition 
        if(oneCount % 3 != 0) return new int[]{-1,-1};
        
        //If oneCount ==0; return any partition
        if(oneCount == 0) return new int[]{0,n-1};
        
        int k = oneCount/3;
        
        //Create Partition
        int i1 = -1, i2 = -1, i3 = -1, j1 = -1, j2 = -1,j3 = -1;
        int currCount = 0; 
        
        for(int i = 0; i < n; i++) {
            if(arr[i] == 1) {
                currCount+=1;
                if(currCount == 1) i1 = i;
                if(currCount == (k+1)) i2 = i;
                if(currCount == (2*k+1)) i3 = i;
                
                if(currCount == k) j1 = i;
                if(currCount == 2*k) j2 = i;
                if(currCount == 3*k) j3 = i;
            }
        }
        
        //Compare 3 partitions
		
		/*
		//O(N) Space Solution
		int[] part1 = Arrays.copyOfRange(arr, i1, j1+1);
        int[] part2 = Arrays.copyOfRange(arr, i2, j2+1);
        int[] part3 = Arrays.copyOfRange(arr, i3, j3+1);
        
        if(!Arrays.equals(part1, part2) || !Arrays.equals(part1, part3)) 
            return new int[]{-1,-1};
		
		*/
        int start = i1, mid = i2,end = i3;
        while(k-- > 0 && arr[start] == arr[mid] && arr[mid] == arr[end]){
            start++;
            mid++;
            end++;
        }
        
        if(k >= 0) return new int[]{-1,-1};
        
        
        //Take care of the trailing zeros
        int first = 0, second = 0, third = 0;
        first = i2-j1-1;
        second = i3-j2-1;
        third = n-j3-1;
        
        if(third > Math.min(first, second)) return new int[]{-1,-1};
        
        return new int[]{j1+third, j2+third+1};
    }
}