最长连续序列-leecode—动态规划

动态规划解法：

    public static int longestConsecutive(int[] nums) {
        if (nums == null || nums.length == 0) {
            return 0;
        }
        if (nums.length == 1) {
            return nums[0];
        }
        int n = nums.length;
        int min = Integer.MAX_VALUE;
        int minIndex = 0;
        for (int i = 0; i < n; i++) {
            if (nums[i] < min) {
                min = nums[i];
                minIndex = i;
            }
        }
        int[] C = new int[n];
        C[minIndex] = 1;
        Integer[] numsInteger = Arrays.stream(nums).boxed().toArray(Integer[]::new);
        for (int i = n - 1; i >= 0; i--) {
            if (nums[i] == min) {
                continue;
            }
            int preIndex = new ArrayList<>(Arrays.asList(numsInteger)).indexOf(nums[i] - 1);
            if (preIndex != -1) {
                C[i] = C[preIndex] + 1;
            } else {
                C[i] = 1;
            }
        }
        int max = Integer.MIN_VALUE;
        for (int i = 0; i < n; i++) {
            if (C[i] > max) {
                max = C[i];
            }
        }
        return max;
    }

未完待优化。