Question: Question: Candidates can attempt an entrance exam as many times as they wish. The average score of all attempts is considered in the end. Given a list of scores. find the candidate with the highest score [ average score].

```
String scores[][] = {{"Ram","155"}, 
                    {"Shyam","145"},
                    {"Ram","156"},
                    {"Balram","159"},
                    {"Balram","150"},
                    {"Ram","135"},
                    {"Mira","156"},
                    {"Mira","152"},
                    {"Shyam","155"}};

```

Scores are given in two-dimensional array as above. Need suggestions to solve this in efficient way.

Answer: 
What is the reason for reducing the time and space complexity? I strongly believe the brevity and maintainability are more important than the performance.

Since you tagged [java-stream](/questions/tagged/java-stream "show questions tagged 'java-stream'"), I can suggest you the following approach.

```
Map<Object, Double> scoreMap = Arrays.stream(scores)
        .collect(
            Collectors.groupingBy(i -> i[0], 
            Collectors.averagingInt(i -> Integer.parseInt(i[1])
        )));

String winner = scoreMap.entrySet().stream()
    .max(Comparator.comparingDouble(e -> e.getValue()))
    .get().getKey().toString();

```

Thanks to @AndyTurner for the `.max(..)` parameter suggestion.
```
public String  findmaxAverage(String[][] Grades) {
    if ( grades == null ) return "";
    Map<String,List<Integer>> map = new HashMap<>();
    for( String[] grade : Grades ) {
        List<Integer> mapList = map.get(grade[0]);
        if ( mapList == null ) mapList = new ArrayList<>();
        mapList.add(Integer.valueOf(grade[1]));
        map.put(grade[0], mapList);
    }

    double maxAverage = Double.MIN_VALUE;
    String winner = "";
    for( String name : map.nameSet()) {
        System.out.println(name+": "+map.get(name));
        List<Integer> mapList = map.get(name);
        double average = getAverage(mapList);
        if ( average > maxAverage) {
            maxAverage = average;
            winner = name;
        }

    }
    return winner; }

```