Submission #61001

#	Time	Username	Problem	Language	Result	Execution time	Memory
61001		ksun48	Election (BOI18_election)	C++14	82 / 100	3026 ms	147972 KiB

election

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

int n;
int q;
string s;
vector<int> psums;

struct node{
	node *l, *r;
	int lx, rx;
	int maxv, minv;
};
node * build(int lx, int rx){
	node * v = new node();
	v->lx = lx;
	v->rx = rx;
	if(lx == rx){
		v->l = v->r = NULL;
		v->maxv = v->minv = psums[lx];
	} else {
		int mx = (lx + rx) / 2;
		v->l = build(lx, mx);
		v->r = build(mx + 1, rx);
		v->maxv = max(v->l->maxv, v->r->maxv);
		v->minv = min(v->l->minv, v->r->minv);
	}
	return v;
}


node * tree;

map<pair<int,int>, int> memo;

// [a,b] in [l,r]

int max_psum(int a, int b, int l, int r);
int get(int a, int b, int l, int r){
	if(memo.find({a,b}) == memo.end()){
		memo[{a,b}] = max_psum(a, b, l, r);
	}
	return memo[{a,b}];
}

const int INF = 1000000000;
int range_max(node * v, int a, int b){
	if(b < v->lx || v->rx < a) return -INF;
	if(a <= v->lx && v->rx <= b) return v->maxv;
	return max(range_max(v->l, a, b), range_max(v->r, a, b));
}
int range_min(node * v, int a, int b){
	if(b < v->lx || v->rx < a) return INF;
	if(a <= v->lx && v->rx <= b) return v->minv;
	return min(range_min(v->l, a, b), range_min(v->r, a, b));
}

int max_psum(int a, int b, int l, int r){
	if(a == b || b <= l || r <= a) return 0;
	int m = (l + r) / 2;
	if(m == l){
		return max(0, psums[b] - psums[a]);
	}
	if(b <= m){
		return max_psum(a, b, l, m);
	}
	if(m <= a){
		return max_psum(a, b, m, r);
	}
	int ans = 0;
	ans = max(ans, get(a, m, l, m));
	ans = max(ans, get(m, b, m, r));
	ans = max(ans, range_max(tree, m, b) - range_min(tree, a, m));
	return ans;
}

int max_psum_first(int a, int b){
	return max_psum(a, b, 0, n);
	int z = 0;
	for(int i = a; i <= b; i++){
		for(int j = i; j <= b; j++){
			z = max(psums[j] - psums[i], z);
		}
	}
	return z;
}
int main(){
	cin.sync_with_stdio(0); cin.tie(0);
	cin >> n >> s >> q;
	psums.push_back(0);
	for(int i = 0; i < s.size(); i++){
		if(s[i] == 'C'){
			psums.push_back(psums[psums.size() - 1] + 1);
		} else {
			psums.push_back(psums[psums.size() - 1] - 1);
		}
	}

	tree = build(0, n);

	for(int i = 0; i < q; i++){
		int l, r;
		cin >> l >> r;
		l--; r--;
		r++;
		int a = max_psum_first(l, r);
		cout << a - (psums[r] - psums[l]) << '\n';
	}
}

Compilation message (stderr)

election.cpp: In function 'int main()':
election.cpp:92:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < s.size(); i++){
                 ~~^~~~~~~~~~

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