第 30 场双周赛

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Words count in article: 436 | Reading time ≈ 2

转变日期格式

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class Solution {
    string ans;
public:
    string reformatDate(string date) {
        int n=date.size(),i;
        ans="";
        for(i=n-4;i<n;i++)ans+=date[i];
        ans+='-';
        for(i=0;date[i]!=' ';i++);
        i++;
        if(date[i]=='J')
        {
            ans+='0';
            if(date[i+1]=='a')ans+='1';
            else if(date[i+2]=='n')ans+='6';
            else ans+='7';
        }
        else if(date[i]=='F')
        {
            ans+='0';
            ans+='2';
        }
        else if(date[i]=='M')
        {
            ans+='0';
            if(date[i+2]=='r')ans+='3';
            else ans+='5';
        }
        else if(date[i]=='A')
        {
            ans+='0';
            if(date[i+1]=='p')ans+='4';
            else ans+='8';
        }
        else if(date[i]=='S')
        {
            ans+='0';
            ans+='9';
        }
        else if(date[i]=='O')
        {
            ans+='1';
            ans+='0';
        }
        else if(date[i]=='N')
        {
            ans+='1';
            ans+='1';
        }
        else if(date[i]=='D')
        {
            ans+='1';
            ans+='2';
        }
        ans+='-';
        if(date[1]>='0'&&date[1]<='9')for(i=0;i<2;i++)ans+=date[i];
        else
        {
            ans+='0';
            ans+=date[0];
        }
        return ans;
    }
};

子数组和排序后的区间和

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class Solution {
    int s[1005],a[1000005];
public:
    int rangeSum(vector<int>& nums, int n, int left, int right) {
        int i,j,m=0,ans=0;
        for(i=0;i<n;i++)s[i+1]=s[i]+nums[i];
        for(i=1;i<=n;i++)for(j=i;j<=n;j++)a[++m]=s[j]-s[i-1];
        sort(a+1,a+m+1);
        for(i=left;i<=right;i++)
        {
            ans+=a[i];
            if(ans>=1000000007)ans-=1000000007;
        }
        return ans;
    }
};

三次操作后最大值与最小值的最小差

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class Solution {
public:
    int minDifference(vector<int>& nums) {
        if(nums.size()<5)return 0;
        sort(nums.begin(),nums.end());
        int n=nums.size(),i,ans=nums[n-1]-nums[0];
        for(i=0;i<4;i++)ans=min(ans,nums[i+n-4]-nums[i]);
        return ans;
    }
};

石子游戏 IV

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class Solution {
    int f[100005];
    bool work(int n)
    {
        if(~f[n])return f[n];
        if(!n)return 0;
        for(int i=1;i*i<=n;i++)if(!work(n-i*i))return f[n]=1;
        return f[n]=0;
    }
public:
    bool winnerSquareGame(int n) {
        memset(f,-1,sizeof(f));
        return work(n);
    }
};
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