CareerCup

Delta encoding

public static List<String> serialize(int ar[]){
int pre = ar[0];
List<String> res = new ArrayList<>();
for(int i=1;i<ar.length;i++){
if(ar[i]-ar[i-1]==1){
continue;
} else {
res.add(pre+"-"+ar[i-1]);
pre=ar[i];
}
}
res.add(""+pre);
return res;
}

public static List<String> serialize(int ar[]){
        int pre = ar[0];
        List<String> res = new ArrayList<>();
        for(int i=1;i<ar.length;i++){
            if(ar[i]-ar[i-1]==1){
                continue;
            } else {
                res.add(pre+"-"+ar[i-1]);
                pre=ar[i];
            }
        }
        res.add(""+pre);
        return res;
    }

replace {{ res.add(""+pre) }} with

{{
int last = ar[ar.length - 1];
res.add((num == last) ? "" + pre : pre + "-" + last);
}}

replace {{ res.add(""+pre) }} with

{{ int last = ar[ar.length - 1]; }}
{{ res.add((num == last) ? "" + pre : pre + "-" + last); }}

public static String encode(int[] arr) {
    	if (arr == null || arr.length == 0) {
    		throw new IllegalArgumentException("input array is null or empty");
    	}
    	
    	if (arr.length == 1) {
    		return Integer.toString(arr[0]);
    	}
    	
    	int start = arr[0];
    	int end = arr[0]; 
    	StringBuilder sb = new StringBuilder();
    	
    	for (int i = 1; i < arr.length; i++) {
    	 
    	 if(arr[i] - arr[i-1] > 1) {
			sb.append(start);
			if (start != end) {
				sb.append("-").append(end);
			}
			sb.append(",");
			start = arr[i];
    	 }
    	 
    	 end = arr[i];
    	}
    	
    	sb.append(start);
    	if (start != end) {
    		sb.append("-").append(end);
    	}
    			
    	return sb.toString();
    
    }

lksa;ldkas;