2019-2020 ACM-ICPC Pacific Northwest Regional Contest

8题。B有傻逼做法但是没出来，不应该。反而最后搞出G出乎意料，lzhnb！

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A：

solver：lzh

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
#define ff first
#define ss second
#define mp make_pair

ll dp1[100010], dp2[100010], ans[100010];
int t[100010], sz[100010], sumt[100010], n, T;
vector<pii> v[100010];
void dfs0(int x, int pre) {
    for (auto i : v[x])
        if (i.ff != pre) {
            dfs0(i.ff, x);
            sz[x] += sz[i.ff];
            sumt[x] += sumt[i.ff];
            dp1[x] += 1ll * sz[i.ff] * i.ss + dp1[i.ff];
            dp2[x] += 1ll * sumt[i.ff] * i.ss + dp2[i.ff];
        }
    sumt[x] += t[x];
    sz[x]++;
}
void dfs(int x, int pre) {
    ans[x] = 1ll * t[x] * dp1[x] + dp2[x];
    for (auto i : v[x])
        if (i.ff != pre) {
            dp1[i.ff] = dp1[x] + 1ll * i.ss * (n - sz[i.ff]) - 1ll * sz[i.ff] * i.ss;
            dp2[i.ff] = dp2[x] + 1ll * (T - sumt[i.ff]) * i.ss - 1ll * sumt[i.ff] * i.ss;
            dfs(i.ff, x);
        }
}
int main() {
    scanf("%d", &n);
    T = 0;
    for (int i = 1; i <= n; i++)
        scanf("%d", &t[i]), T += t[i];
    for (int i = 1; i <= n - 1; i++) {
        int x, y, z;
        scanf("%d%d%d", &x, &y, &z);
        v[x].push_back(mp(y, z));
        v[y].push_back(mp(x, z));
    }
    dfs0(1, -1);
    dfs(1, -1);
    for (int i = 1; i <= n; i++)
        printf("%lld\n", ans[i]);
}

B：

有很好的单调栈sb做法，可惜我最后想到了但是没想清楚，崩了。赛后听了bobby的想法才知道我的想法差在哪里。

/* basic header */
#include <bits/stdc++.h>
/* define */
#define ll long long
#define dou double
#define pb emplace_back
#define mp make_pair
#define sot(a,b) sort(a+1,a+1+b)
#define rep1(i,a,b) for(int i=a;i<=b;++i)
#define rep0(i,a,b) for(int i=a;i<b;++i)
#define eps 1e-8
#define int_inf 0x3f3f3f3f
#define ll_inf 0x7f7f7f7f7f7f7f7f
#define lson (curpos<<1)
#define rson (curpos<<1|1)
/* namespace */
using namespace std;
/* header end */

const int maxn = 2e5 + 10;
int n, k, cnt[maxn], a[maxn], in[maxn], ans[maxn];

int main() {
    for (int i = 0; i < maxn; i++) cnt[i] = in[i] = 0;
    scanf("%d%d", &n, &k);
    for (int i = 1; i <= n; i++) {
        scanf("%d", &a[i]);
        cnt[a[i]]++;
    }
    stack<int>s;
    s.push(a[1]); cnt[a[1]]--; in[a[1]] = 1;
    for (int i = 2; i <= n; i++) {
        cnt[a[i]]--;
        if (in[a[i]]) continue;
        for (; !s.empty() && a[i] < s.top() && cnt[s.top()];) {
            in[s.top()] = 0;
            s.pop();
        }
        s.push(a[i]);
        in[a[i]] = 1;
    }
    for (int i = k; i >= 1; i--) ans[i] = s.top(), s.pop();
    for (int i = 1; i <= k; i++) printf("%d ", ans[i]);
    puts("");
    return 0;
}

C：

solver：lzh、czq

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
#define ff first
#define ss second
#define mp make_pair

vector<int>v[100010];
int vis[100010];
int main() {
    int n, m; scanf("%d%d", &n, &m);
    for (int i = 1; i <= m; i++) {
        int x, y; scanf("%d%d", &x, &y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    queue<pii>q;
    q.push(mp(0, 1));
    while (!q.empty()) {
        pii x = q.front(); q.pop();
        if (vis[x.ss])continue;
        vis[x.ss]++;
        for (auto i : v[x.ss])
            if (!vis[i]) {
                if (i == n) {
                    printf("%d\n", x.ff); return 0;
                }
                q.push(mp(x.ff + 1, i));
            }
    }
}

D：

solver：lzh、czq

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
#define ff first
#define ss second

int main() {
    int a, b, ans = 0; scanf("%d%d", &a, &b);
    while (a != b) {
        if (a % 2)a++;
        else if (a < b) {
            ans += b - a;
            break;
        } else a = a / 2;
        ans++;
    }
    printf("%d\n", ans);
}

E：

solver：lzh、zyh

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
#define ff first
#define ss second
 
char s[100010];
int a[30];
int main(){
    scanf("%s",s+1);
    int n=strlen(s+1);
    for(int i=1;i<=n;i++)a[s[i]-'a'+1]++;
    ll ans=1;
    ll mod=11092019;
    for(int i=1;i<=26;i++)ans=ans*(a[i]+1)%mod;
    printf("%d\n",ans);
}

G：

solver：lzh、czq

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
#define ff first
#define ss second

pii h[200010];
int v1[200010], v2[200010];
int main() {
    int n;
    scanf("%d", &n);
    int cnth = 0, cntv = 0;
    for (int i = 1; i <= n; i++) {
        char s[10];
        int x, y, z;
        scanf("%s%d%d%d", s + 1, &x, &y, &z);
        if (s[1] == 'h')
            h[++cnth] = make_pair(x - z, x - z + y - 1);
        else {
            v1[++cntv] = x - z;
            v2[cntv] = x - z + y - 1;
        }
    }
    sort(v1 + 1, v1 + 1 + cntv);
    sort(v2 + 1, v2 + 1 + cntv);
    ll ans = 0;
    for (int i = 1; i <= cnth; i++) {
        int l, r;
        l = lower_bound(v2 + 1, v2 + 1 + cntv, h[i].ff) - v2;
        r = upper_bound(v1 + 1, v1 + 1 + cntv, h[i].ss) - v1;
        ans += r - l;
    }
    printf("%lld\n", ans);
}

I：

solver：czq

/* basic header */
#include <bits/stdc++.h>
/* define */
#define ll long long
#define dou double
#define pb emplace_back
#define mp make_pair
#define sot(a,b) sort(a+1,a+1+b)
#define rep1(i,a,b) for(int i=a;i<=b;++i)
#define rep0(i,a,b) for(int i=a;i<b;++i)
#define eps 1e-8
#define int_inf 0x3f3f3f3f
#define ll_inf 0x7f7f7f7f7f7f7f7f
#define lson (curpos<<1)
#define rson (curpos<<1|1)
/* namespace */
using namespace std;
/* header end */

map<int, int> front, back, dist;

bool parity(const string &s) {
    bool ret = false;
    for (auto i = s.begin(); i != s.end(); ++i)
        for (auto j = i + 1; j != s.end(); ++j)
            if (*i > *j) ret = !ret;
    return ret;
}

string swap(const string &s, int i, int j) {
    string ret(s);
    ret[i] = s[j]; ret[j] = s[i];
    return ret;
}

bool bfs(const vector<vector<int>> &edges) {
    queue<int> q;
    for (auto i : front) {
        if (i.second == -1) {
            dist[i.first] = 0;
            q.push(i.first);
        } else {
            dist[i.first] = int_inf;
        }
    }
    dist[-1] = int_inf;
    while ((int)q.size()) {
        int u = q.front();
        q.pop();
        if (dist[u] < dist[-1]) {
            for (auto v : edges[u]) {
                auto curr = back.find(v);
                if (dist[curr->second] == int_inf) {
                    dist[curr->second] = dist[u] + 1;
                    q.push(curr->second);
                }
            }
        }
    }

    return dist[-1] != int_inf;
}

bool dfs(const vector<vector<int>> &edges, int u, map<int, int> *front, map<int, int> *back, map<int, int> &dist) {
    if (u == -1) return true;
    for (auto v : edges[u]) {
        if (dist.find((*back)[v])->second == dist.find(u)->second + 1) {
            if (dfs(edges, (*back)[v], front, back, dist)) {
                (*front)[u] = v; (*back)[v] = u;
                return true;
            }
        }
    }
    return false;
}

int main() {
    int n; cin >> n;
    vector<string> words(n);
    unordered_map<string, int> index;
    vector<vector<int>> edges(n), pwords(2);
    for (int i = 0; i < n; ++i) {
        cin >> words[i];
        index[words[i]] = i;
    }
    int __size = words[0].size();
    for (int i = 0; i < n; ++i) {
        int p = (int)parity(words[i]);
        pwords[p].push_back(i);
        if (!p) {
            for (int a = 0; a < __size; ++a) {
                for (int b = a + 1; b < __size; ++b) {
                    auto s = swap(words[i], a, b);
                    auto si = index.find(s);
                    if (si != index.end())
                        edges[i].push_back(si->second);
                }
            }
        }
    }
    for (auto i : pwords[0]) front[i] = -1;
    for (auto i : pwords[1]) back[i] = -1;
    for (int i = 0; i < n; ++i) dist[i] = int_inf;
    // flow
    while (bfs(edges))
        for (auto i : front)
            if (i.second == -1) dfs(edges, i.first, &front, &back, dist);
    int total_flow = 0;
    for (auto i : front) total_flow += (i.second != -1);
    cout << n - total_flow << endl;
    return 0;
}

L：

solver：lzh、zyh

#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
#define ff first
#define ss second

char s[30];
ll ans = 1e18;
const ll ansinf = 1e18;
int a[30], cal[15][15], len;
vector<pii> f[30];
void dfs(int x) {
    if (ans != ansinf)
        return;
    if (x == len - 1) {
        for (int i = 1; i <= len - 1; i++) {
            int tmp = 0;
            for (auto j : f[i])
                tmp += cal[a[j.ff]][a[j.ss]];
            if (tmp % 10 != s[i] - '0')
                return;
        }
        ans = 0;
        for (int i = len; i >= 1; i--)
            ans = ans * 10 + a[i];
        return;
    }
    for (int i = 0; i <= 9; i++) {
        int tmp = 0;
        a[x - len + 1] = i;
        for (auto j : f[x])
            tmp += cal[a[j.ff]][a[j.ss]];
        if (tmp % 10 == s[x] - '0') {
            dfs(x - 1);
        }
    }
}
int main() {
    for (int i = 0; i <= 9; i++)
        for (int j = 0; j <= 9; j++)
            cal[i][j] = i * j % 10;

    scanf("%s", s + 1);
    int n = strlen(s + 1);
    if (n % 2 == 0) {
        printf("-1\n");
        return 0;
    }

    len = (n + 1) / 2;
    for (int i = 1; i <= len; i++)
        for (int j = 1; j <= len; j++)
            f[i + j - 1].push_back(make_pair(i, j));

    char tmpc[30];
    for (int i = 1; i <= n; i++)
        tmpc[i] = s[n - i + 1];
    for (int i = 1; i <= n; i++)
        s[i] = tmpc[i];

    dfs(n);
    if (ans == 1e18)
        printf("-1\n");
    else
        printf("%lld\n", ans);
}

M：

solver：zyh

#include <bits/stdc++.h>
using namespace std;
char Map[2001][2001];
bool vis[2001][2001];
int c[2001][2001];
int cnt = 0;
int mx[] = {0, 0, 1, -1};
int my[] = {1, -1, 0, 0};
void dfs(int x, int y) {
    vis[x][y] = true;
    c[x][y] = cnt;
    for (int i = 0; i < 4; ++i)
        if (!vis[x + mx[i]][y + my[i]] && Map[x + mx[i]][y + my[i]] == '.') {
            dfs(x + mx[i], y + my[i]);
        }
    if (!vis[x - 1][y + 1] && Map[x - 1][y + 1] == '.' && ((Map[x][y + 1] == '.' || Map[x - 1][y] == '.') || (Map[x][y + 1] == '/' && Map[x - 1][y] == '/')) ) dfs(x - 1, y + 1);
    if (!vis[x - 1][y - 1] && Map[x - 1][y - 1] == '.' && ((Map[x][y - 1] == '.' || Map[x - 1][y] == '.') || (Map[x][y - 1] == '\\' && Map[x - 1][y] == '\\'))) dfs(x - 1, y - 1);
    if (!vis[x + 1][y - 1] && Map[x + 1][y - 1] == '.' && ((Map[x][y - 1] == '.' || Map[x + 1][y] == '.') || (Map[x][y - 1] == '/' && Map[x + 1][y] == '/'))) dfs(x + 1, y - 1);
    if (!vis[x + 1][y + 1] && Map[x + 1][y + 1] == '.' && ((Map[x][y + 1] == '.' || Map[x + 1][y] == '.') || (Map[x][y + 1] == '\\' && Map[x + 1][y] == '\\'))) dfs(x + 1, y + 1);
}
int main() {
    int n, m;
    scanf("%d%d", &n, &m);
    for (int i = 2; i <= n + 1; ++i) {
        scanf("%s", Map[i] + 2);
    }
    for (int i = 0; i <= n + 3; ++i) {
        Map[i][0] = Map[i][m + 3] = '$';
    }
    for (int i = 0; i <= m + 3; ++i) {
        Map[0][i] = Map[n + 3][i] = '$';
    }
    for (int i = 1; i <= n + 2; ++i) Map[i][1] = Map[i][m + 2] = '.';
    for (int i = 1; i <= m + 2; ++i) Map[1][i] = Map[n + 2][i] = '.';

    int f1 = 0, f2 = 0;
    for (int i = 1; i <= n + 2; ++i)
        for (int j = 1; j <= m + 2; ++j) {
            if (Map[i][j] == '/' && Map[i][j + 1] == '\\' && Map[i + 1][j] == '\\' && Map[i + 1][j + 1] == '/') ++f1;
            if (Map[i][j] == '.' && !vis[i][j]) {
                cnt++;
                dfs(i, j);
                f2++;
            }
        }
    printf("%d", f1 + f2 - 1);
}