Leetcode第 285 & 288 场周赛 题解

​​第 285 场周赛​​

2210. 统计数组中峰和谷的数量

int countHillValley(vector<int>& nums) {
       vector<int> v; int n = 0;
       for(int i=0;i<nums.size();i++){
           if(n==0) v.push_back(nums[i]),n++;
           else if(v[n-1]!=nums[i]) v.push_back(nums[i]),n++;
       }
       int ans = 0;
       for(int i=1;i<n-1;i++) {
           if(v[i]>v[i-1]&&v[i]>v[i+1]) ans++;
           if(v[i]<v[i-1]&&v[i]<v[i+1]) ans++;
           
       }
       return ans;
   }

2211. 统计道路上的碰撞次数

int countCollisions(string directions) {
      int n = directions.size(),i=0,ans=0;
      while(i<n&&directions[i]=='L') i++;
      stack<char> s;
      while(i<n){
          if(s.size()==0) s.push(directions[i]);
          else{
              char u = s.top();
              if(u=='R'&&directions[i]=='L') {
                  ans+=2;s.pop();
                  while(!s.empty()&&s.top()=='R'){
                      ans+=1;
                      s.pop();
                  }                    
                  s.push('S');
              }
              else if(u=='S'&&directions[i]=='L') {
                  ans+=1;s.pop();
                  s.push('S');
              }
              else if(u=='R'&&directions[i]=='S'){
                  ans+=1;s.pop();
                  while(!s.empty()&&s.top()=='R'){
                      ans+=1;
                      s.pop();
                  }
                  s.push('S');
              }
              else s.push(directions[i]);//R or S
              // cout<<i<<" "<<ans<<endl;
          }
          i++;
      }
      return ans;
  }

2212. 射箭比赛中的最大得分

<int> ans,tmp;
  int val;
  void dfs(int ix,int numArrows,int count,vector<int>& aliceArrows){
      if(ix==aliceArrows.size()){
          if(count>val) {
              val = count;
              tmp[11]+=numArrows;
              ans = tmp;
          }
          return;
      }
      if(numArrows>aliceArrows[ix]) {
          tmp[ix] = aliceArrows[ix]+1;
          dfs(ix+1,numArrows-aliceArrows[ix]-1,count+ix,aliceArrows);
          tmp[ix] = 0;
      }
      dfs(ix+1,numArrows,count,aliceArrows);
  }
  vector<int> maximumBobPoints(int numArrows, vector<int>& aliceArrows) {
      ans.resize(aliceArrows.size());
      tmp.resize(aliceArrows.size());
      dfs(0,numArrows,0,aliceArrows);
      return ans;
  }

2213. 由单个字符重复的最长子字符串

当时没想到

​​第 288 场周赛​​

6037. 按奇偶性交换后的最大数字

int largestInteger(int num) {
    vector<int> a;
    vector<int> b;
    string s = to_string(num);
    for(int i=0;i<s.size();i++) {
        int t = s[i]-'0';
        if(t&1) a.push_back(t);
        else b.push_back(t);
    }
    string ans = "";
    sort(a.begin(),a.end(),greater<int>());
    sort(b.begin(),b.end(),greater<int>());
    int l = 0, r=0;
    for(int i=0;i<s.size();i++) {
        int t = s[i]-'0';
        if(t&1) {
            ans+=to_string(a[l]);
            l++;
        }
        else {
            ans+=to_string(b[r]);
            r++;
        }
    }
    return std::stoi(ans);
}

6038. 向表达式添加括号后的最小结果

string minimizeResult(string expression) {
    string a="",b="";
    int flag = 0;
    for(int i=0;i<expression.size();i++) {
        if(expression[i]=='+') flag=1;
        else if(!flag) a+=expression[i];
        else b+=expression[i];
    }
    // cout<<a<<" "<<b<<endl;
    int ans = INT_MAX;
    string res = "";
    for(int i=0;i<a.size();i++) {
        for(int j=0; j<b.size(); j++) {
            int al,ar,bl,br;
            if(i==0){
                al = 1;ar = std::stoi(a); 
            }
            else {
                al = std::stoi(a.substr(0,i));
                ar = std::stoi(a.substr(i,a.size()-i));
            }
            if(j==b.size()-1) {
                br = 1;
                bl = std::stoi(b);
            }
            else {
                bl = std::stoi(b.substr(0,j+1));
                br = std::stoi(b.substr(j+1,b.size()-j+1));
            }
            // cout<<al<<" "<<ar<<" "<<bl<<" "<<br<<endl;
            int tmp = al*(ar+bl)*br;
            if(tmp<ans){
                ans = tmp;
                res = "";
                if(i!=0) res+=to_string(al);
                res+="("+to_string(ar);
                res+="+"+to_string(bl)+")";
                if(j!=b.size()-1) res+=to_string(br);
            }
        }
    }
    return res;
}

6039. K 次增加后的最大乘积

int maximumProduct(vector<int>& nums, int k) {
    int n = nums.size();
    sort(nums.begin(),nums.end());
    int cost = 0;
    for(int i=0; i<n; i++ ){
        if(i==0) continue;
        else if(cost + i*(nums[i]-nums[i-1]) < k){
            cost += i*(nums[i]-nums[i-1]);
            if(i==n-1){
                for(int j=0;j<i;j++) nums[j] = nums[i];
            }
        }
        else {                
            int x = (k - cost)/i;
            int m = (k-cost)%i;
            int val = nums[i-1];
            for(int j=0;j<i;j++){
                if(m>0) nums[j] = val + x + 1,m--;
                else nums[j] = val + x;
            }
            cost = k;
            break;

        }
    }
    if(cost<k) {
        int x = (k-cost)/n;
        int m = (k-cost)%n;
        for(int i=0;i<n;i++){
            if(m>0) nums[i] = nums[i] + x + 1,m--;
            else nums[i] = nums[i] + x;
        }
        cost = k;
    }
    long long ans = 1;
    int mod = 1e9+7;
    for(int i=0;i<n;i++){
        ans=(ans*(long long)nums[i])%mod;
    }
    return (int)ans;
}

6040. 花园的最大总美丽值

没想到 = =