Submission #439723

#	Time	Username	Problem	Language	Result	Execution time	Memory
439723		cpp219	Election (BOI18_election)	C++14	100 / 100	704 ms	28004 KiB

election

#pragma GCC optimization O2
#pragma GCC optimization "unroll-loop"
#pragma target ("avx2")

#include <bits/stdc++.h>
#define ll int
#define ld long double
#define fs first
#define sc second
using namespace std;
typedef pair<ll,ll> LL;
const ll N = 5e5 + 9;
const ll inf = 1e9 + 7;
string s;
ll n,Q,l,r;

struct Node{
    ll pre,suf,sum,ans;
};
Node st[4*N];

Node combine(Node L,Node R){
    Node kq;
    kq.sum = L.sum + R.sum;
    kq.pre = max(L.pre,L.sum + R.pre);
    kq.suf = max(R.suf,R.sum + L.suf);
    kq.ans = max(L.pre + R.suf,max(L.ans + R.sum,L.sum + R.ans));
    return kq;
}

void build(ll id,ll l,ll r){
    if (l == r){
        if (s[l] == 'C') st[id] = {0,0,-1,0};
        else st[id] = {1,1,1,1}; return;
    }
    ll mid = (l + r)/2;
    build(id*2,l,mid); build(id*2 + 1,mid + 1,r);
    st[id] = combine(st[id*2],st[id*2 + 1]);
}

Node spare = {0,0,0,0};

Node Get(ll id,ll l,ll r,ll u,ll v){
    if (v < l||r < u) return spare;
    if (u <= l&&r <= v) return st[id];
    ll mid = (l + r)/2;
    return combine(Get(id*2,l,mid,u,v),Get(id*2 + 1,mid + 1,r,u,v));
}

int main(){
    ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0);
    #define task "tst"
    if (fopen(task".INP","r")){
        freopen(task".INP","r",stdin);
        //freopen(task".OUT","w",stdout);
    }
    cin>>n>>s; s = " " + s; build(1,1,n);
    cin>>Q;
    while(Q--){
        cin>>l>>r;
        cout<<Get(1,1,n,l,r).ans<<"\n";
    }
}

Compilation message (stderr)

election.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization O2
      | 
election.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
election.cpp:3: warning: ignoring '#pragma target ' [-Wunknown-pragmas]
    3 | #pragma target ("avx2")
      | 
election.cpp: In function 'void build(int, int, int)':
election.cpp:34:9: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
   34 |         else st[id] = {1,1,1,1}; return;
      |         ^~~~
election.cpp:34:34: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
   34 |         else st[id] = {1,1,1,1}; return;
      |                                  ^~~~~~
election.cpp: In function 'int main()':
election.cpp:54:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |         freopen(task".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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