水题5连发：CF496B、609C、560B、500C、HDU5626

最新推荐文章于 2021-05-30 04:19:48 发布

原创最新推荐文章于 2021-05-30 04:19:48 发布 · 817 阅读

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本文分享了在VJ竞赛中解决五道题目的过程与思路。涉及搜索、思维、贪心等算法，并通过具体代码示例展示了每种类型的解题方法。

半夜睡不着在VJ上挂了5道水题练手：http://vjudge.net/contest/143771#overview
A：CF496B
题目传送门：http://codeforces.com/problemset/problem/496/B
类型：搜索

#include<string>
#include<cstdio>
#include<cstring>
#include<map>
#include<queue>
#include<iostream>
using namespace std;
char str[1005];
map<string,int> m;
string ans;
string change1(string str)
{
    int len = str.length();
    for (int i = 0; i < len; i++)
    {
        if (str[i] == '9') str[i] = '0';
        else str[i] = str[i] + 1;
    }
    return str;
}
string change2(string str)
{
    int len = str.length();
    char tmp = str[len-1];
    for (int i = len-2; i >= 0; i--)
        str[i+1] = str[i];
    str[0] = tmp;
    return str;
}
void bfs(string a)
{
    queue<string> q;
    m[a] = 1;
    q.push(a);
    ans = a;
    while (!q.empty())
    {
        string s = q.front();
        q.pop();
        if (s < ans) ans = s;
        string s1 = change1(s);
        string s2 = change2(s);
        if (!m[s1])
        {
            q.push(s1);
            m[s1] = 1;
        }
        if (!m[s2])
        {
            q.push(s2);
            m[s2] = 1;
        }
    }
}
int main()
{
    int n;
    scanf("%d", &n);
    string str;
    cin >> str;
    bfs(str);
    cout << ans << endl;
    return 0;
}

B：CF609C
题目传送门：http://codeforces.com/problemset/problem/609/C
类型：思维

#include<cstdio>
#include<algorithm>
using namespace std;
const int maxn = 100005;
int num[maxn];
int main()
{
    int n,sum = 0,Min,Max;
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
    {
        scanf("%d", &num[i]);
        sum += num[i];
    }
    if (sum % n == 0)
    {
        Min = Max = sum / n;
    }
    else
    {
        Min = sum / n;
        Max = Min + 1;
    }
    int ans1 = 0;
    int ans2 = 0;
    for (int i = 0; i < n; i++)
    {
        if (num[i] < Min)
            ans1 += Min - num[i];
        else if (num[i] > Max)
            ans2 += num[i] - Max;
    }
    printf("%d\n",max(ans1,ans2));
}

C：CF560B
题目传送门：http://codeforces.com/problemset/problem/560/B
类型：简单思维

#include<cstdio>
#include<algorithm>
using namespace std;
#define ok {puts("YES");return 0;}
int main()
{
    int a1,b1,a2,b2,a3,b3;
    scanf("%d %d %d %d %d %d", &a1, &b1, &a2, &b2, &a3, &b3);
    if (a2 + a3 <= a1 && max(b2,b3) <= b1) ok
    if (a2 + b3 <= a1 && max(b2,a3) <= b1) ok
    if (b2 + a3 <= a1 && max(a2,b3) <= b1) ok
    if (b2 + b3 <= a1 && max(a2,a3) <= b1) ok
    if (a2 + a3 <= b1 && max(b2,b3) <= a1) ok
    if (a2 + b3 <= b1 && max(b2,a3) <= a1) ok
    if (b2 + a3 <= b1 && max(a2,b3) <= a1) ok
    if (b2 + b3 <= b1 && max(a2,a3) <= a1) ok
    puts("NO");
    return 0;
}

D：CF500C
题目传送门：http://codeforces.com/problemset/problem/500/C
类型：贪心

#include<cstdio>
int w[505];
int b[1005];
bool vis[505];
int num[505];
int main()
{
    int n,m,cnt = 0,ans = 0;
    scanf("%d %d", &n, &m);
    for (int i = 1; i <= n; i++)
        scanf("%d", &w[i]);
    for (int i = 0; i < m; i++)
    {
        scanf("%d", &b[i]);
        if (vis[b[i]] == 0)
        {
            num[cnt++] = b[i];
            vis[b[i]] = true;
        }
    }
    int j;
    for (int i = 1; i < m; i++)
    {
        for (j = 0; j < cnt; j++)
        {
            if (b[i] == num[j])
                break;
            else
                ans += w[num[j]];
        }
        for (int k = j-1; k >= 0; k--)
        {
            num[k+1] = num[k];
        }
        num[0] = b[i];
    }
    printf("%d\n",ans);
    return 0;
}

E：HDU5626
题目传送门：http://acm.hdu.edu.cn/showproblem.php?pid=5626
类型：简单分类讨论

#include<cstdio>
#include<algorithm>
using namespace std;
typedef long long ll;
long long seed;
inline long long rand(long long l, long long r)
{
    static long long mo = 1e9 + 7, g = 78125;
    return l + ((seed *= g) %= mo) % (r-l+1);
}
const ll INF = 1e15;
int main()
{
    int t,n;
    ll x,y,Min1,Min2,Max1,Max2;
    scanf("%d", &t);
    while (t--)
    {
 //       Min1 = Min2 = INF; //INF多次累加溢出，不要这样用
   //     Max2 = Max2 = -INF;//INF多次累加溢出，不要这样用
        scanf("%d %I64d", &n, &seed);
        x = rand(-1000000000, 1000000000);
        y = rand(-1000000000, 1000000000);
        Min1 = Max1 = x + y;
        Min2 = Max2 = x - y;
    //    printf("%I64d\n",Min1);
        for (int i = 1; i < n; i++)
        {
            x = rand(-1000000000, 1000000000),
            y = rand(-1000000000, 1000000000);
            Min1 = min(Min1,x+y);
            Min2 = min(Min2,x-y);
            Max1 = max(Max1,x+y);
            Max2 = max(Max2,x-y);
        }
        ll ans = max(Max1-Min1,Max2-Min2);
        printf("%I64d\n",ans);
    }
    return 0;
}