Submission #701521

#	Time	Username	Problem	Language	Result	Execution time	Memory
701521		primenumber_zz	Fancy Fence (CEOI20_fancyfence)	C++14	100 / 100	64 ms	8608 KiB

fancyfence

#include<bits/stdc++.h>
using namespace std;

constexpr int mod = 1000000007;

void mpl(int &x,int y) {
    x += y;
    if(x >= mod) x -= mod;
}

struct UnionFind {
    vector<int>par,size,sum;
    UnionFind(int n,vector<int>w) {
        par.resize(n);
        size.resize(n);
        sum.resize(n);
        for(int i = 0; i < n; i++) {
            par[i] = i;
            sum[i] = w[i];
        }
    }
    int find(int x) {
        if(par[x] == x) {
            return x;
        }
        return par[x] = find(par[x]);
    }
    void unite(int u,int v) {
        u = find(u);
        v = find(v);
        if(u == v) {
            return;
        }
        if(size[u] > size[v]) swap(u,v);
        size[v] += size[u];
        mpl(sum[v],sum[u]);
        par[u] = v;
    }
    int consum(int x) {
        return sum[find(x)];
    }
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N;
    cin >> N;
    vector<int>h(N),w(N),cmp;
    for(int i = 0; i < N; i++) {
        cin >> h[i];
        cmp.push_back(h[i]);
    }
    for(int i = 0; i < N; i++) {
        cin >> w[i];
    }
    cmp.push_back(0);
    sort(cmp.begin(),cmp.end());
    cmp.erase(unique(cmp.begin(),cmp.end()),cmp.end());
    vector<vector<int>>tmp(cmp.size());
    for(int i = 0; i < N; i++) {
        h[i] = lower_bound(cmp.begin(),cmp.end(),h[i])-cmp.begin();
        tmp[h[i]].push_back(i);
    }
    UnionFind uf(N,w);
    int ans = 0,sum = 0;
    for(int i = cmp.size()-1; i >= 1; i--) {
        for(int j = 0; j < tmp[i].size(); j++) {
            mpl(sum,1ll*(1+w[tmp[i][j]])*(w[tmp[i][j]])/2%mod);
            if(tmp[i][j] && h[tmp[i][j]-1] >= h[tmp[i][j]]) {
                int sum1 = uf.consum(tmp[i][j]-1);
                int sum2 = uf.consum(tmp[i][j]);
                uf.unite(tmp[i][j]-1,tmp[i][j]);
                mpl(sum,1ll*sum1*sum2%mod);
            }
            if(tmp[i][j]+1 < N && h[tmp[i][j]+1] > h[tmp[i][j]]) {
                int sum1 = uf.consum(tmp[i][j]);
                int sum2 = uf.consum(tmp[i][j]+1);
                uf.unite(tmp[i][j],tmp[i][j]+1);
                mpl(sum,1ll*sum1*sum2%mod);
            }
        }
        int res = 1ll*(1+cmp[i])*cmp[i]/2%mod;
        mpl(res,mod-1ll*(1+cmp[i-1])*cmp[i-1]/2%mod);
        mpl(ans,1ll*res*sum%mod);
    }
    cout << ans << "\n";
}

Compilation message (stderr)

fancyfence.cpp: In function 'int main()':
fancyfence.cpp:68:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   68 |         for(int j = 0; j < tmp[i].size(); j++) {
      |                        ~~^~~~~~~~~~~~~~~

• Subtask 1: 0 / 0
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 15 / 15
• Subtask 5: 15 / 15
• Subtask 6: 18 / 18
• Subtask 7: 27 / 27