滑动窗口leetcode 209和76

一、leetcode 209. 长度最小的子数组

代码：

class Solution {
public:int minSubArrayLen(int target, vector<int>& nums) {int n = nums.size();int left = 0;int sum = 0;int res = 100001;for(int right = 0;right <n;right++){sum += nums[right];while(sum >= target){res = min(res,right-left+1);sum -= nums[left];left++;}}if(res == 100001)res = 0;return res;}
};

二、leetcode76. 最小覆盖子串

代码：

class Solution {
public:string minWindow(string s, string t) {unordered_map<char,int> t_map;unordered_map<char,int> window_map;for(char ch:t){if(t_map.contains(ch)){t_map[ch]++;}else{t_map[ch] = 1;}window_map[ch] = 0;}int s_len = s.size();int left = 0;int ans_left = -1;int ans_len = INT_MAX;for(int right = 0; right <s_len;right++){if(!window_map.contains(s[right]))continue;window_map[s[right]]++;while(check(t_map,window_map) && left <= right){if(right -left+1 <ans_len){ans_len = right -left +1;ans_left = left;}if(t_map.contains(s[left]))window_map[s[left]]--;left++;}}if(ans_left == -1) return "";return s.substr(ans_left,ans_len);}bool check(unordered_map<char,int>& t_map,unordered_map<char,int>& window_map){for(auto p:t_map){if(window_map[p.first] < t_map[p.first])return false;}return true;}
};

class Solution {
public:string minWindow(string s, string t) {unordered_map<char,int> t_map;unordered_map<char,int> window_map;for(char ch:t){if(t_map.contains(ch))t_map[ch]++;elset_map[ch] = 1;}int s_len = s.size();int left = 0;int window_valid_char_cnt = 0;string ans;for(int right = 0; right <s_len;right++){if(++window_map[s[right]] <= t_map[s[right]])window_valid_char_cnt++;while(window_map[s[left]] > t_map[s[left]]){window_map[s[left]]--;left++;}if(window_valid_char_cnt == t.size()){if(ans.empty() || ans.size() > right-left+1)ans = s.substr(left,right-left+1);}}return ans;}
};