【LeetCode】dualseason的个人记录

class Solution {
    public int lengthOfLongestSubstring(String s) {
		HashMap windows = new HashMap();
		int left = 0;
		int right = 0;
		int res = 0;
		while(right < s.length()) {
			Character c = s.charAt(right);
			right++;
			windows.put(c, windows.getOrDefault(c, 0) + 1);
			while(windows.get(c).compareTo(1) > 0 ){
				Character d = s.charAt(left);
				left++;
				windows.remove(d);
			}
			res = Math.max(res, right - left);
		}
		return res;
	}
}

class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode p1 = l1;
        ListNode p2 = l2;
        ListNode dummy = new ListNode(-1);
        ListNode p = dummy;
        int carry = 0;
        while(p1 != null || p2 != null || carry > 0){
            int val = carry;
            if(p1 != null){
                val += p1.val;
                p1 = p1.next;
            }
            if(p2 != null){
                val += p2.val;
                p2 = p2.next;
            }
            carry = val/10;
            val = val % 10;
            p.next = new ListNode(val);
            p = p.next;
        }
        return dummy.next;
    }
}

class Solution {
    public int maxArea(int[] height) {
        // 总体算法往中间缩,面积有收缩的趋势
        // 面积(求最大) = 长(逐渐收缩) * 宽
        // 等出结论: 宽势必要逐渐变长才符合题意
        int left = 0, right = height.length - 1;
        int res = 0;
        while (left < right) {
            // 记录当前容量,有可能最大
            int cur_area = Math.min(height[left], height[right]) * (right - left);
            res = Math.max(res, cur_area);
            // 但向两边缩的时候,需要遵循高度边长的规则
            // 那边高我就要那个
            if (height[left] < height[right]) {
                // 右边高,保留右边,舍弃左边,左边右移换新的
                left++;
            } else {
                // 左边高,保留左边,舍弃有边
                right--;
            }
        }
        return res;
    }
}