Added faster implementation for square

This commit is contained in:
Anthony Wang 2020-05-14 10:37:04 -05:00
parent 75cdebec70
commit 4e39f23a9b
3 changed files with 90 additions and 1 deletions

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.gitignore vendored
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out out
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!/**/
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.vscode/square vendored

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square.cpp Normal file
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#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
if (fopen("in", "r")) freopen("in", "r", stdin), freopen("out", "w", stdout);
int T;
cin >> T;
for (int t = 0; t < T; ++t) {
cout << "Case #" << t + 1 << ": ";
int R, C;
cin >> R >> C;
vector<vector<int>> S(R); // we have to use vector of vector because R or C could be 1e5
vector<pair<int, int>> check; // set of candidate competitors to check
ll ans = 0, sum = 0;
for (int i = 0; i < R; ++i) {
S[i].resize(C);
for (int j = 0; j < C; ++j) {
cin >> S[i][j];
sum += S[i][j];
check.emplace_back(i, j);
}
}
vector<vector<vector<int>>> neighbor(R);
for (int i = 0; i < R; ++i) {
neighbor[i].resize(C);
for (int j = 0; j < C; ++j) {
neighbor[i][j].resize(4);
neighbor[i][j][0] = i > 0 ? i - 1 : -1;
neighbor[i][j][1] = i < R - 1 ? i + 1 : -1;
neighbor[i][j][2] = j > 0 ? j - 1 : -1;
neighbor[i][j][3] = j < C - 1 ? j + 1 : -1;
}
}
while (1) {
vector<pair<int, int>> elim; // vector to store eliminated competitors
for (auto& x : check) { // examine every candidate competitor
int i = x.first, j = x.second, sum = 0, num = 0;
if (S[i][j]) {
if (neighbor[i][j][0] != -1) sum += S[neighbor[i][j][0]][j], ++num;
if (neighbor[i][j][1] != -1) sum += S[neighbor[i][j][1]][j], ++num;
if (neighbor[i][j][2] != -1) sum += S[i][neighbor[i][j][2]], ++num;
if (neighbor[i][j][3] != -1) sum += S[i][neighbor[i][j][3]], ++num;
if (num * S[i][j] < sum) elim.emplace_back(i, j);
}
}
check.clear(); // clear check for finding candidates for next round
ans += sum;
for (auto& x : elim) {
int i = x.first, j = x.second;
if (S[i][j]) {
sum -= S[i][j];
S[i][j] = 0;
if (neighbor[i][j][0] != -1) {
neighbor[neighbor[i][j][0]][j][1] = neighbor[i][j][1];
check.emplace_back(neighbor[i][j][0], j);
}
if (neighbor[i][j][1] != -1) {
neighbor[neighbor[i][j][1]][j][0] = neighbor[i][j][0];
check.emplace_back(neighbor[i][j][1], j);
}
if (neighbor[i][j][2] != -1) {
neighbor[i][neighbor[i][j][2]][3] = neighbor[i][j][3];
check.emplace_back(i, neighbor[i][j][2]);
}
if (neighbor[i][j][3] != -1) {
neighbor[i][neighbor[i][j][3]][2] = neighbor[i][j][2];
check.emplace_back(i, neighbor[i][j][3]);
}
}
}
if (elim.empty()) break;
}
cout << ans << '\n';
}
}