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Add dp/knapsack.cc 

Signed-off-by: subcrip <contact@subc.rip>
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subcrip 2024-05-29 19:17:38 +08:00
parent 14900a2165
commit f8e979f114
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// Part of the code from a Cf problem to demonstrate how to dump the path from a knapsack-dp solution.
for (int j = 1; j <= m; ++j) {
auto [t, p, idx] = events[i][j - 1];
for (int k = 0; k <= 100; ++k) {
dp[j][k] = dp[j - 1][k];
}
for (int k = 0; k <= 100; ++k) {
int new_percent = min(100, dp[j - 1][k].second + p); // In this problem we just omit the capacity over 100.
if (dp[j][new_percent].first > dp[j - 1][k].first + t) {
dp[j][new_percent] = {dp[j - 1][k].first + t, dp[j - 1][k].second + p};
}
}
}
ll tm = dp[m][100].first;
if (tm + start > a[i]) {
cout << -1 << '\n';
return;
} else {
int k = dp[m][100].second;
for (int j = m; j >= 1; --j) {
auto [t, p, idx] = events[i][j - 1];
if (dp[j][min(100, k)] < dp[j - 1][min(100, k)]) { // Find the last step of the construction process.
k -= p; // Prepare to find the next one.
res.emplace_back(idx); // Add the current item as part of the solution.
}
}
start += tm;
}