每周一练（34）

如何判断list是否递增且是连续的

 

public static boolean isContinuous1(List<Integer> nums) {

        AtomicBoolean continuous = new AtomicBoolean(true);
        AtomicInteger counter = new AtomicInteger(nums.get(0));
        nums.forEach(item -> {
            if (counter.getAndIncrement() != item) {
                continuous.set(false);
            }
        });

        return continuous.get();
    }

 

还有更优雅的写法吗

可以借助lambda

public static boolean isContinuous2(List<Integer> nums) {
        AtomicInteger counter = new AtomicInteger(nums.get(0));
        return nums.stream().allMatch(i -> i == counter.getAndIncrement());
    }

 

跑一波单测

public static void main(String[] args) {
        List<Integer> nums = ImmutableList.of(2, 3, 4, 5, 6);
        System.out.println(isContinuous1(nums));
        System.out.println(isContinuous2(nums));

        List<Integer> nums1 = ImmutableList.of(2, 3, 4, 5, 6, 9, 10);
        System.out.println(isContinuous1(nums1));
        System.out.println(isContinuous2(nums1));
    }

输出：

true
true
false
false

 

如果是递增但不连续呢，如果是递减且不连续还包括负数呢

如果是按照一定规则递增呢，比如n的平方