File size: 2,863 Bytes
1fd0050 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 | #include <iostream>
#include <vector>
#include <queue>
#include <map>
#include <algorithm>
using namespace std;
long long n, k;
map<pair<int, int>, long long> cache;
long long query(int r, int c) {
if (r < 1 || r > n || c < 1 || c > n) {
// This case should not be reached with valid logic.
// It's a safeguard against out-of-bounds access.
return -1;
}
if (cache.count({r, c})) {
return cache[{r, c}];
}
cout << "QUERY " << r << " " << c << endl;
long long val;
cin >> val;
return cache[{r, c}] = val;
}
void done(long long ans) {
cout << "DONE " << ans << endl;
}
void solve_min_pq() {
priority_queue<pair<long long, pair<int, int>>, vector<pair<long long, pair<int, int>>>, greater<pair<long long, pair<int, int>>>> pq;
for (int i = 1; i <= n; ++i) {
long long val = query(i, 1);
pq.push({val, {i, 1}});
}
long long result = -1;
for (int i = 0; i < k; ++i) {
pair<long long, pair<int, int>> top = pq.top();
pq.pop();
result = top.first;
int r = top.second.first;
int c = top.second.second;
if (c < n) {
long long val = query(r, c + 1);
pq.push({val, {r, c + 1}});
}
}
done(result);
}
void solve_max_pq() {
long long k_prime = n * n - k + 1;
priority_queue<pair<long long, pair<int, int>>> pq;
for (int i = 1; i <= n; ++i) {
long long val = query(i, n);
pq.push({val, {i, n}});
}
long long result = -1;
for (int i = 0; i < k_prime; ++i) {
pair<long long, pair<int, int>> top = pq.top();
pq.pop();
result = top.first;
int r = top.second.first;
int c = top.second.second;
if (c > 1) {
long long val = query(r, c - 1);
pq.push({val, {r, c - 1}});
}
}
done(result);
}
long long count_le(long long x) {
long long count = 0;
int r = 1, c = n;
while (r <= n && c >= 1) {
if (query(r, c) <= x) {
count += c;
r++;
} else {
c--;
}
}
return count;
}
void solve_binary_search() {
long long low = query(1, 1);
long long high = query(n, n);
long long ans = high;
while (low <= high) {
long long mid = low + (high - low) / 2;
if (count_le(mid) >= k) {
ans = mid;
high = mid - 1;
} else {
low = mid + 1;
}
}
done(ans);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> k;
long long query_limit = 50000;
if (n + k - 1 <= query_limit) {
solve_min_pq();
}
else if (n + (n * n - k + 1) - 1 <= query_limit) {
solve_max_pq();
}
else {
solve_binary_search();
}
return 0;
} |