2023年百度之星程序设计竞赛初赛1题解

每次出题都出其不意---->群友蓝桥国三，百度之星ac一道题

根据官方的视频题解整理

依据难度的划分

第五题：促销糖果

 分析：从答案出发想吃K个糖果，必定有k个糖纸，考虑换购，则有一张糖纸是不可以换的（因为你必须至少要买一颗糖果需要特判

ac代码

java 

import java.util.Scanner;
import java.util.ArrayList;
import java.io.*;
import java.util.StringTokenizer;
public class Main{
    static BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter pw=new PrintWriter(new OutputStreamWriter(System.out));
    static StringTokenizer tokenizer=new StringTokenizer("");
    static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }
    static int nextInt() throws IOException
    {
        return Integer.parseInt(next());
    }
    static double Double() throws IOException
    {
        return Double.parseDouble(next());
    }
    static long nextlong() throws IOException
    {
        return Long.parseLong(next());
    }
    public static void main(String[] args)throws IOException {
        
         ArrayList<Long>ans=new ArrayList<>();
        
         long t=nextlong();
         while(t-->0)
         {
             long p=nextlong();
             long k=nextlong();
             if(k==0)
             {
                 ans.add(k);
             }
             else{
                  k-=(k-1)/p;
                 ans.add(k);
             }
           
         }
         for(Long i:ans)
         {
            pw.println(i);
         }
         pw.flush();
    }
}

c++

#include <iostream>
#include <vector>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int t;
    cin >> t;
    
    vector<long long> ans;
    
    while (t--) {
        long long p, k;
        cin >> p >> k;
        
        if (k == 0) {
            ans.push_back(k);
        } else {
            k -= (k - 1) / p;
            ans.push_back(k);
        }
    }
    
    for (long long i : ans) {
        cout << i << '\n';
    }
    
    cout.flush();
    
    return 0;
}

 

第一题公园

 思路 ：T 和F汇合与点g然后一起到达N,用三段dfs.然后枚举三段值求最小

java 代码

import java.util.Scanner;
import java.util.ArrayList;
import java.util.Arrays;

public class Main{
    static int a, b, c;
    static int s1, s2, n, m;
    static ArrayList<Integer>[] son = new ArrayList[40010];
    static int[][] dis = new int[3][40010];
    static int[] que = new int[40010];

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        a = input.nextInt();
        b = input.nextInt();
        c = input.nextInt();
        s1 = input.nextInt();
        s2 = input.nextInt();
        n = input.nextInt();
        m = input.nextInt();
        
        for (int i = 1; i <= n; i++) {
            son[i] = new ArrayList<>(); // Initialize each ArrayList
        }

        for (int i = 1; i <= m; i++) {
            int u = input.nextInt();
            int v = input.nextInt();
            son[u].add(v);
            son[v].add(u);
        }
        calc(dis[0], s1);
        calc(dis[1], s2);
        calc(dis[2], n);
        long ans = Long.MAX_VALUE; // Initialize ans to maximum value
        for (int i = 1; i <= n; i++) {
            if (dis[0][i] != -1 && dis[1][i] != -1 && dis[2][i] != -1) {
                ans = Math.min(ans, 1L * dis[0][i] * a + 1L * dis[1][i] * b + 1L * dis[2][i] * (a + b - c));
            }
        }
        long op = ans == Long.MAX_VALUE ? -1 : ans; // Use Long.MAX_VALUE for comparison
        System.out.println(op);
    }

    public static void calc(int[] dis, int s) {
        int tall = 1;
        Arrays.fill(dis, -1);
        dis[s] = 0;
        que[1] = s;
        for (int i = 1; i <= tall; i++) {
            int cur = que[i];
            for (int v : son[cur]) {
                if (dis[v] == -1) {
                    dis[v] = dis[cur] + 1;
                    que[++tall] = v;
                }
            }
        }
    }
}

c++代码

#include <iostream>
#include <vector>
#include <algorithm>
#include <climits>

using namespace std;

const int MAXN = 40010;

int a, b, c;
int s1, s2, n, m;
vector<int> son[MAXN];
int dis[3][MAXN];
int que[MAXN];

void calc(int dis[], int s) {
    int tall = 1;
    fill(dis, dis + MAXN, -1);
    dis[s] = 0;
    que[1] = s;
    for (int i = 1; i <= tall; i++) {
        int cur = que[i];
        for (int v : son[cur]) {
            if (dis[v] == -1) {
                dis[v] = dis[cur] + 1;
                que[++tall] = v;
            }
        }
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> a >> b >> c >> s1 >> s2 >> n >> m;

    for (int i = 1; i <= n; i++) {
        son[i].clear(); // Clear each vector
    }

    for (int i = 1; i <= m; i++) {
        int u, v;
        cin >> u >> v;
        son[u].push_back(v);
        son[v].push_back(u);
    }
    calc(dis[0], s1);
    calc(dis[1], s2);
    calc(dis[2], n);
    long long ans = LLONG_MAX; // Initialize ans to maximum value
    for (int i = 1; i <= n; i++) {
        if (dis[0][i] != -1 && dis[1][i] != -1 && dis[2][i] != -1) {
            ans = min(ans, 1LL * dis[0][i] * a + 1LL * dis[1][i] * b + 1LL * dis[2][i] * (a + b - c));
        }
    }
    long long op = (ans == LLONG_MAX) ? -1 : ans; // Use LLONG_MAX for comparison
    cout << op << '\n';

    return 0;
}

 

 思路二分答案:

AC代码 java

import java.io.*;
import java.util.StringTokenizer;
import java.math.BigInteger;

public class Main {
    static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    static PrintWriter pw = new PrintWriter(new OutputStreamWriter(System.out));
    static StringTokenizer tokenizer = new StringTokenizer("");

    static String next() throws IOException {
        while (!tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }

    static int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    static BigInteger nextBigInteger() throws IOException {
        return new BigInteger(next());
    }

    static int n;
    static int m;
    static int[] s = new int[100010];
    static int[] v = new int[100010];

    public static void main(String[] args) throws IOException {
        n = nextInt();
        m = nextInt();
        for (int i = 1; i <= n; i++) {
            s[i] = nextInt();
            v[i] = nextInt();
        }
        BigInteger l = BigInteger.ONE;
        BigInteger r = BigInteger.valueOf(Long.MAX_VALUE);
        BigInteger ans = BigInteger.valueOf(-1);
        while (l.compareTo(r) <= 0) {
            BigInteger mid = l.add(r).shiftRight(1); // (l + r) / 2
            if (cheak(mid)) {
                ans = mid;
                r = mid.subtract(BigInteger.ONE);
            } else {
                l = mid.add(BigInteger.ONE);
            }
        }
        pw.println(ans);

        pw.flush();
    }

    public static boolean cheak(BigInteger t) {
        BigInteger sum = BigInteger.ZERO;
        BigInteger max = BigInteger.ZERO;
        for (int i = 1; i <= n; i++) {
            BigInteger cur = t.subtract(BigInteger.valueOf(s[i])).multiply(BigInteger.valueOf(v[i])).max(BigInteger.ZERO);
            max = max.max(cur);
            sum = sum.add(cur);
        }
        return sum.subtract(max).compareTo(BigInteger.valueOf(m)) >= 0;
    }
}