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  1. Ice Cream Parlor
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Ice Cream Parlor

  • trip2ken
     + 0 comments

    Java 8 - Used an Index Sort to order the values. One time through the list and to find the correct pair.

        public static List<Integer> icecreamParlor(int m, List<Integer> arr) {
        List<Integer> rtn = new ArrayList<>();
        
        // Index Sort
        int[] indices = IntStream.range(0, arr.size())
                .boxed()
                .sorted(Comparator.comparingInt(i -> arr.get(i)))
                .mapToInt(Integer::intValue)
                .toArray();
        
        // Close in on the solution
        int l = 0;
        int h = arr.size()-1;
        while(l<h && arr.get(indices[l]) + arr.get(indices[h]) != m) {
            int vh = arr.get(indices[h]);
            int vl = arr.get(indices[l]);
            
            if (vh >= m || (vh + vl) > m)
                --h;
            else 
                ++l;           
        }
        
        // sort result into asscending order.
        rtn.add(Math.min( indices[l], indices[h] )+1); 
        rtn.add(Math.max( indices[l], indices[h] )+1); 
        
        return rtn ;
    }