LeetCode周赛190

LeetCode周赛190题解-1455-1456-1457-1458

class Solution {
public:
    void SplitString(const std::string& s, std::vector<std::string>& v, const std::string& c){
        std::string::size_type pos1, pos2;
         pos2 = s.find(c);
        pos1 = 0;
        while(std::string::npos != pos2)
         {
             v.push_back(s.substr(pos1, pos2-pos1));
 
             pos1 = pos2 + c.size();
             pos2 = s.find(c, pos1);
        }
          if(pos1 != s.length())
            v.push_back(s.substr(pos1));
    }
    
    int isPrefixOfWord(string sentence, string searchWord) {
        vector<string> t;
        int pos = 0;
        int len = searchWord.length();
        SplitString(sentence, t, " ");
        for (int i = 0; i < t.size(); i++) {
            if (t[i].substr(0, len) == searchWord) {
                
                return i + 1;
            } 
            
        }
        
        return -1;
    }
};

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class Solution {
public:
    bool check(char a, string s) {
        for (int j = 0; j < 5; j++) 
           if (a == s[j]) return true;
        return false;
    }
    
    int maxVowels(string s, int k) {
        string a = "aeiou";
        int max = 0;
        vector<int> n(s.length(), 0);
        
        for (int i = 0; i  < s.length(); i++) {
            
                if (check(s[i], a)) {
                    n[i] = 1;
                    
                } 
            
        }
        
        for (int i = 0; i < k; i++) {
            if (n[i] == 1) max++;
        }
        
        int cnt = max;
        for (int i = k ; i < s.length(); i++) {
            if (check(s[i], a)) { //是元音
                if (n[i - k] == 1) continue; //右移以后左边元音被移除
                else {
                    cnt++; //左边不是元音
                }
            } else { //不是元音
                if (n[i - k] == 1) cnt--; //左边元音被移出
            }
            max = max < cnt ? cnt : max;
        }
        return max;

    }
};

---

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int check(int *cnt) { //检查得到的结点的是否只有一个奇数
        int odd = 0;
        for(int i = 0; i <= 9; i++) {
            if(cnt[i]&1) { // &1判断是否为奇数
                odd++;
            }
        }
        if(odd <= 1) { //只有一个奇数或者没有奇数如：22
            return 1;
        }
        return 0;
    }
    int dfs(TreeNode *root, int *cnt) {
        if(root == nullptr) { // 递归出口
            return 0;
        }
        cnt[root->val] ++;
        if(root->left == nullptr && root->right == nullptr) { //判断是否到达叶节点 然后调用check
            int anw = check(cnt);
            cnt[root->val]--; //统计完减去
            return anw;
        }
        int anw = 0;
        if(root->left != nullptr) {
            anw += dfs(root->left, cnt);
        }
        if(root->right != nullptr) {
            anw += dfs(root->right, cnt);
        }
        cnt[root->val] --; //统计完减去
        return anw;
    }
    int pseudoPalindromicPaths (TreeNode* root) {
        int cnt[10] = {0};
        return dfs(root, cnt);
    }
};

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class Solution {
public:
    int maxDotProduct(vector<int>& nums1, vector<int>& nums2) {
        int sz1=nums1.size(),sz2=nums2.size();
        vector<vector<int>> dp(sz1+1,vector<int>(sz2+1,-1e8));

        for(int i=1;i<=sz1;i++){
            for(int j=1;j<=sz2;j++){
                //1.1
                dp[i][j]=nums1[i-1]*nums2[j-1];
                //1.2
                dp[i][j]=max(dp[i][j],nums1[i-1]*nums2[j-1]+dp[i-1][j-1]);
                //2
                dp[i][j]=max(dp[i][j],dp[i][j-1]);
                //3
                dp[i][j]=max(dp[i][j],dp[i-1][j]);
                //4
                dp[i][j]=max(dp[i][j],dp[i-1][j-1]);
            }
        }
        return dp[sz1][sz2];
    }
};