2018年南海区小学生程序设计竞赛详细答案

1 魔术卡片

AC代码

#include <iostream>
#include <cstdio>
using namespace std;

int main()
{
    freopen("hide.in", "r", stdin);
    freopen("hide.out", "w", stdout);
    
    int a1, b1, a2, b2;
    cin >> a1 >> b1 >> a2 >> b2;
    
    if (a1 < b1)
    {
        swap(a1, b1);
    }
    
    if (a2 < b2)
    {
        swap(a2, b2);
    }
    
    if((a1 >= a2 && b1 >= b2) || (a1 <= a2 && b1 <= b2))
    {
        cout << 1;
    }
    else
    {
        cout << 2;
    }
    
    return 0;
}

2 均分计算

AC代码

#include <iostream>
#include <algorithm>
#include <cstdio>
using namespace std;

int main(int argc, const char * argv[])
{
    freopen("average.in", "r", stdin);
    freopen("average.out", "w", stdout);

    int n;
    cin >> n;
    int a[n];
    double score, sum = 0;
    for (int i = 0; i < n; i++)
    {
        cin >> a[i];
        sum += a[i];
    }

    sort(a, a + n);

    sum -= (a[0] + a[n - 1]);

    score = sum / (n - 2);

    printf("%.2f", score);

    return 0;
}

3 出发能量

AC代码

#include<cstdio>

int main()
{
  freopen("start.in", "r", stdin);
  freopen("start.out", "w", stdout);
  
  int n;
  scanf("%d", &n);
  
  int sum = 0;
  int ans = 0;
  for(int i = 0; i < n; i++)
  {
    int x;
    scanf("%d", &x);
    sum += x;
    if(sum < 0)
    {
      ans += (-1 * sum);
      sum = 0;
    }
  }
  
  printf("%d", ans);
  
  return 0;
}

4 衰减

AC代码

#include<bits/stdc++.h>
using namespace std;

int n, ans[10], ansN, tot;

void dfs(int num)
{
    if(1 == num)
    {
        tot++;
        printf("%d-", n);

        for(int i=1; i<ansN; i++)
        {
            printf("%d-", ans[i]);
        }
        printf("%d\n", ans[ansN]);

        return;
    }

    num >>= 1;
    for(int i=1; i<=num; i++)
    {
        ans[++ansN] = i;
        dfs(i);
        --ansN;
    }
}

int main()
{
    freopen("down.in","r",stdin);
    freopen("down.out","w",stdout);

    scanf("%d", &n);
    dfs(n);
    printf("%d", tot);

    return 0;
}

5 拆除桥墩

AC代码

#include<bits/stdc++.h>
using namespace std;

const int MAXINF=0x7fffffff;
const int MININF=0x80000000;

int n,m,l,d[50002];

bool check(int dmin)
{
    int s=0, tot=0;
    for(int i=1; i<=n; i++)
    {
        s += d[i];
        if(s < dmin)
        {
            tot++;
        }
        else
        {
            s = 0;
        }
    }

    return (tot <= m);
}

int main()
{
    freopen("remove.in", "r", stdin);
    freopen("remove.out", "w", stdout);
    cin >> l >> n >> m;
    for(int i=1; i<=n; i++)
    {
        cin >> d[i];
    }

    d[n+1] = l-d[n];
    for(int i=n; i>=2; i--)
    {
        d[i] = d[i] - d[i-1];
    }

    n++;

    int left = MAXINF, right = 0;
    for(int i=1; i<=n; i++)
    {
        left = min(left, d[i]);
        right += d[i];
    }

    while(left + 1 < right)
    {
        int mid = (left + right) >> 1;
        if(check(mid))
        {
            left = mid;
        }
        else
        {
            right = mid;
        }
    }

    cout << left;

    return 0;
}

6 卜克游戏

AC代码
#include<bits/stdc++.h>
using namespace std;

int f[3002],P[3002],S[3002],n;

int main()
{
    freopen("poker.in","r",stdin);
    freopen("poker.out","w",stdout);

    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>P[i];
    }

    for(int i=1;i<=n;i++)
    {
        cin>>S[i];
        S[i]+=S[i-1];
    }

    for(int i=1;i<=n;i++)
    {
        f[i]=f[i-1];
        for(int j=i-1;j>=1;j--)
        {
            if(P[i]==P[j])
            {
                f[i]=max(f[i],S[i]-S[j-1]+f[j-1]);
            }
        }
    }

    cout<<f[n];

    return 0;
}