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Codeforces Round 966 (Div. 3)

时间:2024-08-29 10:37:52浏览次数:14  
标签:966 int Codeforces long read while Div dis define

A. Primary Task

if-else语句练习,判断前两个字符是否为"10",并判断之后的字符是否大于1

点击查看代码
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define pii pair<int, int>

int read()
{
    int x = 0, f = 0; char c = getchar();
    while (c < '0' || c > '9') f = c == '-', c = getchar();
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f ? -x : x;
}

const int N = 1e4 + 5;
char s[N];

int main()
{
    int T = read();
    while(T--)
    {
        scanf("%s", s + 1);
        int len = strlen(s + 1);
        if(s[1] == '1' && s[2] == '0' && ((len > 3 && s[3] >= '1') || (len == 3 && s[3] >= '2'))) printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}

B. Seating in a Bus

模拟

点击查看代码
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define pii pair<int, int>

int read()
{
    int x = 0, f = 0; char c = getchar();
    while (c < '0' || c > '9') f = c == '-', c = getchar();
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f ? -x : x;
}

const int N = 2e5 + 5;
int a[N], vis[N];

int main()
{
    int T = read();
    while(T--)
    {
        int n = read();
        for(int i = 1; i <= n; ++i) a[i] = read();
        for(int i = 1; i <= n; ++i) vis[i] = 0;
        vis[a[1]] = 1;
        int flag = 1;
        for(int i = 2; i <= n; ++i)
        {
            int ner = 0;
            if(a[i] > 1) ner |= vis[a[i] - 1];
            if(a[i] < n) ner |= vis[a[i] + 1];
            if(ner == 0){ flag = 0; break; }
            vis[a[i]] = 1;
        }
        if(flag) printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}

C. Numeric String Template

还是模拟,每个数字第一次出现映射到一个字符上,之后再出现直接判断,字符第一次出现同理

点击查看代码
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define pii pair<int, int>

int read()
{
    int x = 0, f = 0; char c = getchar();
    while (c < '0' || c > '9') f = c == '-', c = getchar();
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f ? -x : x;
}

const int N = 2e5 + 5;
int a[N], b[N];
int id1[N], id2[N];
char s[N];
void solve()
{
    int n = read();
    for(int i = 1; i <= n; ++i) a[i] = b[i] = read();
    sort(b + 1, b + n + 1);
    int x = unique(b + 1, b + n + 1) - (b + 1);
    for(int i = 1; i <= n; ++i) a[i] = lower_bound(b + 1, b + x + 1, a[i]) - b;
    int m = read();
    while(m--)
    {
        scanf("%s", s + 1);
        int flag = 1, len = strlen(s + 1);
        if(len != n){ printf("NO\n"); continue; }
        for(int i = 1; i <= n; ++i) id1[i] = -1;
        for(int i = 1; i <= n; ++i)
        {
            if(id1[a[i]] == -1) id1[a[i]] = s[i] - 'a';
            else if(id1[a[i]] != s[i] - 'a') flag = 0;
            if(!flag) break;
        }
        for(int i = 0; i <= 25; ++i) id2[i] = -1;
        for(int i = 1; i <= len; ++i)
        {
            if(id2[s[i] - 'a'] == -1) id2[s[i] - 'a'] = a[i];
            else if(id2[s[i] - 'a'] != a[i]) flag = 0;
            if(!flag) break;
        }
        if(flag) printf("YES\n");
        else printf("NO\n");
    }
}

int main()
{
    int T = read();
    while(T--) solve();
    return 0;
}

D. Right Left Wrong

注意到 \(LLRR\) 取 \((1, 3)(2, 4)\) 和 \((1, 4)(2, 3)\) 是等价的,于是直接取所有区间只有包含没有相交的情况,即用双指针从两端向中间扫即可

点击查看代码
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define pii pair<int, int>

int read()
{
    int x = 0, f = 0; char c = getchar();
    while (c < '0' || c > '9') f = c == '-', c = getchar();
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f ? -x : x;
}

const int N = 2e5 + 5;
int a[N];
char s[N];
ll sum[N];

void solve()
{
    int n = read();
    for(int i = 1; i <= n; ++i) a[i] = read(), sum[i] = sum[i - 1] + a[i];
    scanf("%s", s + 1);
    int l = 1, r = n;
    ll ans = 0;
    while(l < r)
    {
        while(l <= n && s[l] != 'L') ++l;
        while(r >= 1 && s[r] != 'R') --r;
        if(l < r) ans += sum[r] - sum[l - 1];
        ++l, --r;
    }
    printf("%lld\n", ans);
}

int main()
{
    int T = read();
    while(T--) solve();
    return 0;
}

E. Photoshoot for Gorillas

简单计算一下一个格子被多少个边长为 \(K\) 的子方阵包含,那么这个格子里的数就会贡献这么多次,贪心的让大数放到次数多的格子里

点击查看代码
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define pii pair<int, int>

int read()
{
    int x = 0, f = 0; char c = getchar();
    while (c < '0' || c > '9') f = c == '-', c = getchar();
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f ? -x : x;
}

const int N = 2e5 + 5;
int a[N];
int cnt[N];

bool cmp(int a, int b){ return a > b; }

void solve()
{
    int n = read(), m = read(), K = read(), W = read(), tot = 0;
    for(int i = 1; i <= W; ++i) a[i] = read();
    sort(a + 1, a + W + 1, cmp);
    for(int x = 1; x <= n; ++x)
        for(int y = 1; y <= m; ++y)
        {
            int lx = max(1, x - K + 1), rx = min(n - K + 1, x);
            int ly = max(1, y - K + 1), ry = min(m - K + 1, y);
            cnt[++tot] = 1ll * (rx - lx + 1) * (ry - ly + 1);
        }
    sort(cnt + 1, cnt + tot + 1, cmp);
    ll ans = 0;
    for(int i = 1; i <= W; ++i) ans += 1ll * a[i] * cnt[i];
    printf("%lld\n", ans);
}

int main()
{
    int T = read();
    while(T--) solve();
    return 0;
}

F. Color Rows and Columns

首先想到的是贪心,即一个 \(a \times b\) 的矩形,填满一行或一列需要 \(\min\{a, b\}\) 步

这样贪心的取,发现当 \(1 \times 1\) 时一次性填了一行和一列,答案 + 2

贪心不完全对,转而考虑背包 \(DP\)

需要注意的是:想要答案 + a + b ,需要 \(a \times b\) 步,想要答案 + a + b - 1 ,也需要 \(a \times b\) 步

点击查看代码
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define pii pair<int, int>

int read()
{
    int x = 0, f = 0; char c = getchar();
    while (c < '0' || c > '9') f = c == '-', c = getchar();
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f ? -x : x;
}

const int inf = 0x3f3f3f;
int dp[2][105], a[1005], b[1005];
vector< pair<int, int> > x[1005];

void init(int id)
{
    x[id].clear();
    int A = a[id], B = b[id], sum = 0, K = 0;
    while(A && B)
    {
        sum += A, --B, ++K;
        if(A > B) swap(A, B);
        if(A == 0) x[id].emplace_back(pair<int, int>(K, sum)), ++K;
        x[id].emplace_back(pair<int, int>(K, sum));
    }
}

void solve()
{
    int n = read(), K = read();
    for(int i = 1; i <= n; ++i)
    {
        a[i] = read(), b[i] = read();
        if(a[i] > b[i]) swap(a[i], b[i]);
        init(i);
    }
    for(int i = 1; i <= K; ++i) dp[0][i] = inf;
    int ans = inf;
    for(int i = 1, op = 1; i <= n; ++i, op ^= 1)
    {
        for(int j = 0; j <= K; ++j) dp[op][j] = dp[op ^ 1][j];
        for(auto [w, val] : x[i])
        {
            for(int j = w; j <= K; ++j)
                dp[op][j] = min(dp[op][j], dp[op ^ 1][j - w] + val);
        }
        ans = min(ans, dp[op][K]);
    }
    if(ans == inf) printf("-1\n");
    else printf("%d\n", ans);
}

int main()
{
    int T = read();
    while(T--) solve();
    return 0;
}

G. Call During the Journey

最短路魔改,松弛操作时分三种情况:

  1. 直接走路过去,不受任何限制

  2. 坐车过去,需要保证下车时间 \(\le t1\) 或者上车时间 \(\ge t2\)

  3. 等到 \(t2\) 再上车

点击查看代码
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define pii pair<int, int>

int read()
{
    int x = 0, f = 0; char c = getchar();
    while (c < '0' || c > '9') f = c == '-', c = getchar();
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f ? -x : x;
}

const ll inf = 0x7fffffffffff;
const int N = 1e5 + 5;  
int n, m;
int t0, t1, t2;

struct node
{
    int v, l1, l2;
    node(){ v = l1 = l2 = 0; }
    node(int x, int y, int z){ v = x, l1 = y, l2 = z; }
};

vector<node> e[N];

ll dis[N];
bool vis[N];
priority_queue< pair<int, int> > q;

bool check(int t)
{
    // printf("t = %d\n", t);
    for(int i = 1; i <= n; ++i) dis[i] = inf, vis[i] = 0;
    dis[1] = t;
    q.push(pair<int, int>(-dis[1], 1));
    while(!q.empty())
    {
        int u = q.top().second ;
        q.pop();
        if(vis[u]) continue;
        vis[u] = 1;
        // printf("u = %d, dis = %lld\n", u, dis[u]);
        for(auto [v, l1, l2] : e[u])
        {
            int flag = 0;
            if(dis[v] > dis[u] + l2)
            {
                dis[v] = dis[u] + l2;
                flag = 1;
            }
            if(dis[v] > dis[u] + l1 && ((dis[u] + l1 <= t1) || (dis[u] >= t2)))
            {
                dis[v] = dis[u] + l1;
                flag = 1;
            }
            if(dis[u] <= t2 && dis[v] > t2 + l1)
            {
                dis[v] = t2 + l1;
                flag = 1;
            }
            if(flag) q.push(pair<int, int>(-dis[v], v));
        }
    }
    if(dis[n] <= t0) return true;
    else return false;
}

void solve()
{
    n = read(), m = read();
    t0 = read(), t1 = read(), t2 = read();
    for(int i = 1; i <= n; ++i) e[i].clear();
    for(int i = 1; i <= m; ++i)
    {
        int u = read(), v = read(), l1 = read(), l2 = read();
        e[u].emplace_back(node(v, l1, l2));
        e[v].emplace_back(node(u, l1, l2));
    }
    int l = -1, r = t0;
    while(l < r)
    {
        int mid = (l + r + 1) >> 1;
        if(check(mid)) l = mid;
        else r = mid - 1;
    }
    printf("%d\n", l);
}

int main()
{
    int T = read();
    while(T--) solve();
    return 0;
}

H. Ksyusha and the Loaded Set

转化题意为,最初所有数都为 \(1\) ,集合中包含的数为 \(0\) ,三种操作:

  1. 加入集合一个数,等价于将此位置设为 \(0\)

  2. 删去集合一个数,等价于将此位置设为 \(1\)

  3. 询问集合中1的连续段长度 \(\ge k\) 的最小左端点

权值线段树搞就完了

终于知道多测的意义了,专门卡 \(O(值域)\) 的算法

注意到每次测试时都重建一颗一模一样的树,时间消耗主要在这里,不优

又注意到每个测试中的操作数是 \(O(n)\) 的,考虑撤销操作

只在一开始建树,之后每次用时撤销前面的测试的操作

总结

  • 权值线段树遇上多测,考虑撤销操作
点击查看代码
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long
#define pii pair<int, int>

int read()
{
    int x = 0, f = 0; char c = getchar();
    while (c < '0' || c > '9') f = c == '-', c = getchar();
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f ? -x : x;
}

const int N = 2e5 + 5;
int n, m, a[N];

struct node
{
    int mx, lsum, rsum, len;
    node(){ mx = lsum = rsum = len = 0; }
    node friend operator + (node a, node b)
    {
        node c;
        c.mx = max(a.mx , b.mx );
        c.mx = max(c.mx , a.rsum + b.lsum );
        c.len = a.len + b.len ;
        c.lsum = a.lsum + ((a.lsum == a.len ) ? b.lsum : 0);
        c.rsum = b.rsum + ((b.rsum == b.len ) ? a.rsum : 0);
        return c;
    }
};

#define ls(x) (x << 1)
#define rs(x) (x << 1 | 1)

node A[8388605 + 10];

void build(int k, int l, int r)
{
    if(l == r)
    {
        A[k].mx = A[k].lsum = A[k].rsum = A[k].len = 1;
        return ;
    }
    int mid = (l + r) >> 1;
    build(ls(k), l, mid), build(rs(k), mid + 1, r);
    A[k] = A[ls(k)] + A[rs(k)];
}

void update(int k, int l, int r, int pos, int val)
{
    if(l == r)
    {
        A[k].mx = A[k].lsum = A[k].rsum = val;
        return ;
    }
    int mid = (l + r) >> 1;
    if(pos <= mid) update(ls(k), l, mid, pos, val);
    else update(rs(k), mid + 1, r, pos, val);
    A[k] = A[ls(k)] + A[rs(k)];
}

int query(int k, int l, int r, int len)
{
    if(l == r) return l;
    int mid = (l + r) >> 1;
    if(A[ls(k)].mx >= len) return query(ls(k), l, mid, len);
    if(A[ls(k)].rsum + A[rs(k)].lsum >= len) return mid - A[ls(k)].rsum + 1;
    return query(rs(k), mid + 1, r, len);
}

pair<int, int> sta[N << 1];
int top;

void solve()
{
    n = read();
    for(int i = 1; i <= n; ++i) a[i] = read();
    m = read();
    top = 0;
    for(int i = 1; i <= n; ++i) update(1, 1, 4e6, a[i], 0), sta[++top] = pair<int, int>(a[i], 0);
    while(m--)
    {
        char c;
        int x;
        scanf(" %c %d", &c, &x);
        if(c == '-') update(1, 1, 4e6, x, 1), sta[++top] = pair<int, int>(x, 1);
        if(c == '+') update(1, 1, 4e6, x, 0), sta[++top] = pair<int, int>(x, 0);
        if(c == '?') printf("%d ", query(1, 1, 4e6, x));
    }
    while(top)
    {
        update(1, 1, 4e6, sta[top].first , sta[top].second ^ 1);
        --top;   
    }
    printf("\n");
}

int main()
{
    int T = read();
    build(1, 1, 4e6);
    while(T--) solve();
    return 0;
}

标签:966,int,Codeforces,long,read,while,Div,dis,define
From: https://www.cnblogs.com/wenqizhi/p/18386129

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