05 - 双指针与滑动窗口¶

def two_sum_sorted(nums, target):
    l, r = 0, len(nums) - 1
    while l < r:
        s = nums[l] + nums[r]
        if s == target:
            return [l, r]
        if s < target:
            l += 1
        else:
            r -= 1
    return []

from collections import defaultdict

def longest_without_repeat(s: str) -> int:
    cnt = defaultdict(int)
    l = 0
    ans = 0
    for r, ch in enumerate(s):
        cnt[ch] += 1
        while cnt[ch] > 1:
            cnt[s[l]] -= 1
            l += 1
        ans = max(ans, r - l + 1)
    return ans