题解 | #最长严格上升子数组(一)#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param nums int整型一维数组 
     * @return int整型
     */
    public int maxSubArrayLengthTwo(int[] nums) {
        // write code here

        if (nums.length < 2) {
            return nums.length;
        }
        if (nums.length == 2) {
            return nums[0] == 100000 ? 1 : 2;
        }

        int[] dp = new int[nums.length];
        Arrays.fill(dp, Integer.valueOf(1));
        int ans = 1;
        for (int i = 1; i < nums.length; i++) {
            if (nums[i] > nums[i - 1]) {
                dp[i] = dp[i - 1] + 1;
                ans = Math.max(ans, dp[i]);
            }
        }
        for (int currentIndex = 1; currentIndex < dp.length; currentIndex++) {
            if (dp[currentIndex] == 1) {
                ans = Math.max(ans, dp[currentIndex - 1] == 100000 ? dp[currentIndex] : dp[currentIndex - 1] + 1);
                continue;
            }
            int previousIndex = currentIndex - dp[currentIndex];
            if (previousIndex > -1 && nums[previousIndex + 1] > 1) {
                ans = Math.max(ans, dp[currentIndex] + 1);
            }
            if (previousIndex > -1 && nums[previousIndex + 2] - nums[previousIndex] >= 2) {
                ans = Math.max(ans, dp[currentIndex] + dp[previousIndex]);
            }
            if (previousIndex - 1 > -1 && nums[previousIndex + 1] - nums[previousIndex - 1] >= 2) {
                ans = Math.max(ans, dp[currentIndex] + dp[previousIndex]);
            }
        }
        return ans;
    }
}