A comprehensive solution to: http://codingbat.com/prob/p189576

maxSpan.java

public int maxSpan(int[] nums) {
    HashMap<Integer, int[]> spanMap = new HashMap();

    int max = 0;

    for(int i = 0; i < nums.length; ++i) {
        if(!spanMap.containsKey(nums[i])) {
            spanMap.put(nums[i], new int[]{i,i});
        } else {
            spanMap.get(nums[i])[1] = i;
        }

        int span = spanMap.get(nums[i])[1] -
                   spanMap.get(nums[i])[0] + 1;

        max = (span > max) ? span : max;
    }

    return max;
}