C++ 算法竞赛、06 周赛篇 | AcWing 第97场周赛

AcWing 第97场周赛

4944 热身计算

#include <bits/stdc++.h>

using namespace std;

int a, b;

int main() {
    cin >> a >> b;
    cout << min(a, b);
    cout << " " << abs(a - b) / 2;
    return 0;
}

4945 比大小

4945. 比大小 - AcWing题库

考查K进制转换十进制

#include <bits/stdc++.h>

using namespace std;

int const N = 15;

int x, y, n, m;
int nums[N];
int main() {
    long long res_a = 0, res_b = 0;
    cin >> n >> x;
    for (int i = 1; i <= n; i++) {
        cin >> nums[i];
    }
    long long t = 1;
    for (int i = n; i >= 1; i--) {
        res_a += nums[i] * t;
        t *= x;
    }

    cin >> m >> y;
    for (int i = 1; i <= m; i++) {
        cin >> nums[i];
    }
    t = 1;
    for (int i = m; i >= 1; i--) {
        res_b += nums[i] * t;
        t *= y;
    }
    if (res_a > res_b)
        puts(">");
    else if (res_a < res_b)
        puts("<");
    else
        puts("=");
    return 0;
}

4946 叶子节点

4946. 叶子节点 - AcWing题库

无向边要开两倍点数的数组，见常量 M
cnt 统计每个有效叶子节点的个数
st 记录遍历过的点，让每个点只遍历一次
dfs
- count 统计还有几条边没走，0 条则为叶子节点
- 遍历所有子节点，根据子节点颜色分两种情况
  - 黑色：更新最大长度，连续长度+1
  - 白色：不更新最大长度，连续长度置 0

#include <bits/stdc++.h>

using namespace std;

int const N = 1e5 + 10, M = 2e5 + 10;
int h[N], e[M], ne[M], idx;
int color[N];
int n, m;

void add(int a, int b) { e[idx] = b, ne[idx] = h[a], h[a] = idx++; }

int cnt;
bool st[N];
void dfs(int u, int black_max, int black_now) {
    st[u] = true;
    int count = 0;
    for (int i = h[u]; ~i; i = ne[i]) {
        int j = e[i];
        if (st[j]) continue;
        count++;
        if (color[j])
            dfs(j, max(black_max, black_now + 1), black_now + 1);
        else
            dfs(j, black_max, 0);
    }

    if (!count)
        if (black_max <= m) cnt++;
}

int main() {
    cin >> n >> m;
    memset(h, -1, sizeof h);
    for (int i = 1; i <= n; i++) cin >> color[i];
    for (int i = 1; i <= n; i++) {
        int x, y;
        cin >> x >> y;
        add(x, y);
        add(y, x);
    }

    dfs(1, 0, color[1]);
    cout << cnt;

    return 0;
}