abc363+cf960div.2+牛客周赛49轮

C - Avoid K Palindrome 2 (atcoder.jp)

思路:

罗列出排列的每一种情况,再根据题目要求进行判断

代码:

cpp 复制代码
void solve()
{
	ll n, k;
	cin >> n >> k;
	string s;
	vector<char>a;
	cin >> s;
	for (int i = 0; i < n; i++)a.push_back(s[i]);
	sort(a.begin(), a.end());
	bool ok, flag;
	ll ans = 0;
	while (true)
	{
		ok = true;
		for (int i = 0; i <= n - k; i++)
		{
			flag = true;
			for (int j = 0; j < k; j++)
			{
				if (a[i + j] != a[i + 1 + k - j])
				{
					flag = false;
				}
			}
			if (flag)ok = false;
		}
		if (ok)ans++;
		if(!next_permutation(a.begin(),a.end()))break;
	}
	cout << ans << endl;
	return;
}

D - Palindromic Number (atcoder.jp)

思路其实很简单,根据需要的i-th进行判断即可

cpp 复制代码
#define _CRT_SECURE_NO_WARNINGS 1
//------ 棘手大学 世界第一 ------//
#include<bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<vector>
#include<queue>
#include<map>
#include<cmath>
using namespace std;
//gcd最大公约数,lcm最小公倍数
typedef long long ll;
#define IOS ios::sync_with_stdio(false); cin.tie(nullptr), cout.tie(nullptr);
priority_queue<int, vector<int>, greater<int>> pq;
map<int, int>mp;
const int N = 2e6 + 10;
long long sum[60], a[60];
long long n;
int ans[1010], len, b[1010];
ll pow(int x) {
    long long res = 1;
    for (int i = 1; i <= x; i++)
        res *= 10;
    return res;
}
int main() {
    IOS;
    for (int i = 1; i <= 37; i++) {
        int mi = ((i + 1) / 2 - 1);
        a[i] = 1LL * 9 * pow(mi);
        sum[i] = sum[i - 1] + a[i];
    }
    cin >> n;
    if (n <= 1)
    {
        cout << "0" << endl;
        return 0;
    }
    n -= 1;
    int pos = lower_bound(sum + 1, sum + 38, n) - sum;
    if (n == sum[pos - 1])pos--;
    while (n) {
        b[++len] = n % 10;
        n /= 10;
    }
    for (int i = 1, j = len; i <= len; i++, j--)
        ans[i] = b[j];
    ans[1]--; ans[len]++;
    if (ans[1] == 0 && ans[2] == 0)ans[2] = 9;
    int now = len;
    while (ans[now] >= 10) {
        ans[now - 1] += ans[now] / 10;
        ans[now] %= 10;
        now--;
    }
    int l = len, r = len + 1;
    if (pos % 2 == 1)l--;
    while (l >= 1) {
        ans[r] = ans[l];
        l--; r++;
    }
    l = 1, r--;
    while (ans[l] == 0)
        l++;
    while (ans[r] == 0)
        r--;
    for (int i = l; i <= r; i++)
        cout << ans[i];
}

Problem - A - Codeforces

思路:

由题意可知两者每次肯定都会做出最佳选择(即选取最大),所以我们只需要判断最大值是奇数还是偶数即可(因为是Alice先手,所以奇数A必胜,否则B胜)

代码:

cpp 复制代码
//该段代码经过修改仅提供思路,不能AC
void solve()
{
	ll a[N];
	ll n;
	cin >> n;
	for (int i = 1; i <= n; i++)
	{
		cin >> a[n];
		mp[a[n]]++;
	}
	sort(a + 1, a + 1 + n, cmp);
	ll flag = 1;
	for (auto k : a)
	{
		if (mp[a[k]] % 2 != 0)
		{
			flag = 0;
		}
	}
	if (flag)cout << "NO" << endl;
	else
		cout << "NO" << endl;
	return;
}

Problem - B - Codeforces

代码:

cpp 复制代码
#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include <stdbool.h>

#define N 2000010
typedef long long ll;

ll n, t, x, y;
ll dp[N];

void solve() {
    scanf("%lld %lld %lld", &n, &x, &y);
    for (ll i = 1; i <= n; i++) {
        if (i >= y && i <= x) {
            dp[i] = 1;
        }
    }
    for (ll i = y - 1; i >= 1; i -= 2) {
        dp[i] = -1;
        if (i - 1 >= 1) {
            dp[i - 1] = 1;
        }
    }
    for (ll i = x + 1; i <= n; i += 2) {
        dp[i] = -1;
        if (i + 1 <= n) {
            dp[i + 1] = 1;
        }
    }
    for (ll i = 1; i <= n; i++)
        printf("%lld ", dp[i]);
    printf("\n");
}

int main() {
    scanf("%lld", &t);
    while (t--) {
        solve();
    }
    return 0;
}

Problem - C - Codeforces

代码:

cpp 复制代码
void solve() {
    int n;
    cin >> n;
    vector<ll> a(n);
    for (int i = 0; i < n; ++i)
        cin >> a[i];

    ll res = 0;

    for (int i = 0; i < 2; ++i) {
        vector<bool> vis(n + 1);
        ll ma = 0;
        for (ll& x : a) {
            if (vis[x])
                ma = max(ma, x);
            vis[x] = true;
            res += x;
            x = ma;
        }
    }

    for (int i = 0; i < n; ++i)
        res += (n - i) * a[i];

    cout << res << endl;
}

C-嘤嘤不想买东西喵_牛客周赛 Round 49(重现赛) (nowcoder.com)

本质就是求最大连续子段和

代码:

cpp 复制代码
#define _CRT_SECURE_NO_WARNINGS 1
//------ 棘手大学 世界第一 ------//
#include<bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<vector>
#include<queue>
#include<map>
#include<cmath>
using namespace std;
//gcd最大公约数,lcm最小公倍数
typedef long long ll;
#define IOS ios::sync_with_stdio(false); cin.tie(nullptr), cout.tie(nullptr);
priority_queue<int, vector<int>, greater<int>> pq;
map<int, int>mp;
const int N = 2e6 + 10;
int mod(string a, ll b)//高精度a除以单精度b
{
	ll n = 0;
	for (int i = 0; i < a.size(); i++)  n = (n * 10 + (a[i] - '0')) % b;  //求出余数
	return n;
}
string gcd(string a, ll b)  // 欧几里得算法
{
	while (b != 0)
	{
		ll temp = b;
		b = mod(a, b);
		a = to_string(temp);
	}
	return a;
}
int gcd1(int a, int b)//a、b不可以为0(很快)
{
	while (b ^= a ^= b ^= a %= b);
	return a;
}
int gcd2(int a, int b)//a、b可以为0(很快)
{
	if (b) while ((a %= b) && (b %= a));
	return a + b;
}
int lcm1(int a, int b) {
	return a * b / gcd1(a, b);
}
bool cmp(ll x, ll y)
{
	return x > y;
}
ll a[N], dp[N];
void solve()
{
	ll n, x;
	cin >> n >> x;
	for (int i = 1; i <= n; i++)
		cin >> a[i], a[i] -= x;
	ll ans = 0;
	for (int i = 1; i <= n; i++)
	{
		dp[i] = max(a[i], dp[i - 1] + a[i]);
	}
	for (int i = 1; i <= n; i++)
	{
		ans = max(ans, dp[i]);
	}
	cout << ans << endl;
	return;
}
int main()
{
	IOS;
	solve();

	return 0;
}

D-嘤嘤不想求异或喵_牛客周赛 Round 49(重现赛) (nowcoder.com)

求区间异或和(以后直接套用模板算了)

代码:

cpp 复制代码
ll xor_prefix(ll n) {
	switch (n % 4) {
	case 0: return n;
	case 1: return 1;
	case 2: return n + 1;
	case 3: return 0;
	}
	return 0;
}
int xor_range(ll L, ll R) {//区间所有整数异或和
	return xor_prefix(R) ^ xor_prefix(L - 1);
}
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