Submission #712769

#	Time	Username	Problem	Language	Result	Execution time	Memory
712769		ssense	Election (BOI18_election)	C++14	0 / 100	2 ms	1748 KiB

election

#include <bits/stdc++.h>
typedef long long  ll;
using namespace std;
#define vint vector<int>
#define pb push_back
#define sc second
#define fr first

void solve()
{
    int n;
    cin >> n;
    string s;
    cin >> s;
    int now = 0;
    vint pref(n+2), suffix(n+2);
    for(int i = 1; i <= n; i++)
    {
        if(s[i-1] == 'C')
        {
            pref.push_back(--now);
        }
        else
        {
            pref.push_back(++now);
        }
    }
    now = 0;
    for(int i = n; i >= 1; i--)
    {
        if(s[i-1] == 'C')
        {
            suffix[i] = --now;
        }
        else
        {
            suffix[i] = ++now;
        }
    }
    vector<vector<pair<int, int>>> sparsePrefix, sparseSuffix;
    sparsePrefix.assign(20, vector<pair<int, int>>(n+5));
    sparseSuffix.assign(20, vector<pair<int, int>>(n+5));
    for(int i = 1; i <= n; i++)
    {
        sparsePrefix[0][i] = {pref[i], i};
        sparseSuffix[0][i] = {suffix[i], i};
    }
    for(int l = 1; l < 19; l++)
    {
        for(int i = 1; i <= n; i++)
        {
            if(i+(1<<l)-1 > n){break;}
            //PREFIX
            int mx = max(sparsePrefix[l-1][i].fr, sparsePrefix[l-1][i+(1<<(l-1))].fr);
            int ind = 0;
            if(mx == sparsePrefix[l-1][i].fr){ind = sparsePrefix[l-1][i].sc;}
            else{ind = sparsePrefix[l-1][i+(1<<(l-1))].sc;}
            sparsePrefix[l][i] = {mx, ind};
            //SUFFIX
            mx = max(sparseSuffix[l-1][i].fr, sparseSuffix[l-1][i+(1<<(l-1))].fr);
            ind = 0;
            if(mx == sparseSuffix[l-1][i+(1<<(l-1))].fr){ind = sparseSuffix[l-1][i+(1<<(l-1))].sc;}
            else{ind = sparseSuffix[l-1][i].sc;}
            sparseSuffix[l][i] = {mx, ind};
        }
    }
    int q;
    cin >> q;
    while(q--)
    {
        int l, r;
        cin >> l >> r;
        //PREFIX
        int dist = 31-__builtin_clz(r-l+1);
        int mxPref = max(sparsePrefix[dist][l].fr, sparsePrefix[dist][r-(1<<(dist))+1].fr);
        int indPref = 0;
        if(mxPref == sparsePrefix[dist][l].fr){indPref = sparsePrefix[dist][l].sc;}
        else{indPref = sparsePrefix[dist][r-(1<<(dist))+1].sc;}
        mxPref-=pref[l];
        
        int mxSuff = max(sparseSuffix[dist][l].fr, sparseSuffix[dist][r-(1<<l)+1].fr);
        int indSuff = 0;
        if(mxSuff == sparseSuffix[dist][r-(1<<l)+1].fr){indSuff = sparseSuffix[dist][r-(1<<l)+1].sc;}
        else{indSuff = sparseSuffix[dist][l].sc;}
        mxSuff-=suffix[r];
        mxPref = max(0, mxPref);
        mxSuff = max(0, mxSuff);
        int ans = mxPref+mxSuff;
        if(indPref < indSuff || mxPref == 0 || mxSuff == 0)
        {
            cout << ans << endl;
            continue;
        }
        assert(1 == 0);
        int nwr = indSuff-1;
        int beforePref = 0;
        if(nwr >= l)
        {
            int temp = 31-__builtin_clz(nwr-l+1);
            beforePref+=max(sparsePrefix[temp][l].fr, sparsePrefix[temp][nwr-(1<<(temp))+1].fr)-pref[l-1];
            beforePref = max(0, beforePref);
        }
        int nwl = indPref+1;
        int beforeSuff = 0;
        if(nwl <= r)
        {
            int temp = 31-__builtin_clz(r-nwl+1);
            beforeSuff+=max(sparseSuffix[temp][nwl].fr, sparseSuffix[temp][r-(1<<(temp))+1].fr)-suffix[r+1];
            beforeSuff = max(0, beforeSuff);
        }
        ans-=min(mxPref-beforePref, mxSuff-beforeSuff);
        cout << ans << endl;
    }
}

int main(){
    int t = 1;
    //cin >> t;
    while (t--) {
        solve();
    }
}


/*
11
CCCTTTTTTCC
3
1 11
4 9
1 6
 */

• Subtask 1: 0 / 28
• Subtask 2: 0 / 54
• Subtask 3: 0 / 18