#include<iostream>
#include<algorithm>
#define FOR(i, x, y) for (int i = x; i < y; i++)
typedef long long ll;
using namespace std;
struct Node {
int l_max, r_max, tot, ans;
Node operator+(Node b) {
Node ret;
ret.l_max = max(l_max, b.l_max + tot);
ret.r_max = max(r_max + b.tot, b.r_max);
ret.tot = tot + b.tot;
ret.ans = max(max(ans + b.tot, b.ans + tot), l_max + b.r_max);
return ret;
}
};
Node segtree[2000001];
char s[500001];
int n;
void build(int node = 1, int l = 1, int r = n) {
if (l == r) {
if (s[l] == 'T') segtree[node] = {1, 1, 1, 1};
else segtree[node] = {0, 0, -1, 0};
} else {
int mid = (l + r) / 2;
build(node * 2, l, mid);
build(node * 2 + 1, mid + 1, r);
segtree[node] = segtree[node * 2] + segtree[node * 2 + 1];
}
}
Node query(int a, int b, int node = 1, int l = 1, int r = n) {
if (l > b || r < a) return {0, 0, 0, 0};
if (l >= a && r <= b) return segtree[node];
int mid = (l + r) / 2;
return query(a, b, node * 2, l, mid) + query(a, b, node * 2 + 1, mid + 1, r);
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
freopen("elections.in", "r", stdin);
freopen("elections.out", "w", stdout);
cin >> n; assert(1 <= n && n <= 500000);
FOR(i, 1, n + 1) cin >> s[i];
build();
int q;
cin >> q; // assert(1 <= q && q <= 500000);
while (q--) {
int a, b;
cin >> a >> b;
cout << query(a, b).ans << '\n';
}
return 0;
}
Compilation message
election.cpp: In function 'int main()':
election.cpp:48:15: error: 'assert' was not declared in this scope
48 | cin >> n; assert(1 <= n && n <= 500000);
| ^~~~~~
election.cpp:3:1: note: 'assert' is defined in header '<cassert>'; did you forget to '#include <cassert>'?
2 | #include<algorithm>
+++ |+#include <cassert>
3 | #define FOR(i, x, y) for (int i = x; i < y; i++)
election.cpp:46:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
46 | freopen("elections.in", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
election.cpp:47:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
47 | freopen("elections.out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
