#224673 (C++17) No.626 Randomized 01 Knapsack

• 問題: No.626 Randomized 01 Knapsack
• ユーザー: kimiyuki
• 提出日時: 2017-12-18 09:25:13
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: WA
• 実行時間: -
• コード長: 2,753 bytes
• コンパイル時間: 1,440 ms
• コンパイル使用メモリ: 100,000 KB
• 最終ジャッジ日時: 2025-01-05 05:53:07
• ジャッジサーバーID （参考情報）: judge5 / judge4

ファイルパターン	結果
other	AC * 2 WA * 23

ソースコード

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#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#define repeat(i,n) for (int i = 0; (i) < (n); ++(i))
#define repeat_reverse(i,n) for (int i = (n)-1; (i) >= 0; --(i))
typedef long long ll;
template <typename T> bool setmax(T & l, T const & r) { if (not (l < r)) return false; l = r; return true; }
template <typename T> bool setmin(T & l, T const & r) { if (not (r < l)) return false; l = r; return true; }
using namespace std;
int main() {
    int n; ll lim_w; cin >> n >> lim_w;
    vector<ll> v(n), w(n); repeat (i,n) cin >> v[i] >> w[i];
    ll max_v = *max_element(v.begin(), v.end());
    ll max_w = *max_element(w.begin(), w.end());
    ll sum_w = accumulate(w.begin(), w.end(), 0ll);
    ll sum_v = accumulate(v.begin(), v.end(), 0ll);
    ll ans = 0;
    if (sum_w <= lim_w) {
        ans = sum_v;
    } else if (n <= 30) { // branch and bound
        /* sort by the efficiency */ {
            vector<int> xs(n); repeat (i,n) xs[i] = i;
            sort(xs.begin(), xs.end(), [&](int i, int j) -> bool { return v[i] * w[j] > v[j] * w[i]; });
            vector<ll> tv = v, tw = w;
            repeat (i,n) { v[i] = tv[xs[i]]; w[i] = tw[xs[i]]; }
        }
        function<void (int, ll, ll)> f = [&](int i, ll cur_v, ll cur_w) {
            if (lim_w < cur_w) return; // not executable
            if (i == n) { setmax(ans, cur_v); return; } // terminate
            ll lr_v = cur_v; // linear relaxation
            ll lr_w = cur_w;
            int j;
            for (j = i; j < n and lr_w + w[j] <= lim_w; ++ j) { // greedy
                lr_w += w[j];
                lr_v += v[j];
            }
            if (lr_w == lim_w or j == n) { setmax(ans, lr_v); return; } // accept greedy
            double lr_ans = lr_v + v[j] * ((lim_w - lr_w) /(double) w[j]);
            if (lr_ans <= ans) return; // bound
            f(i+1, cur_v+v[i], cur_w+w[i]);
            f(i+1, cur_v,      cur_w     );
        };
        f(0, 0, 0);
    } else if (max_w <= 1000) { // dynamic programming
        vector<ll> dp(lim_w+1);
        repeat (i,n) {
            repeat_reverse (j, lim_w-w[i]+1) {
                setmax(dp[j + w[i]], dp[j] + v[i]);
            }
        }
        repeat (j, lim_w+1) {
            setmax(ans, dp[j]);
        }
    } else if (max_v <= 1000) { // dynamic programming
        vector<ll> dp(sum_v+1, lim_w+1);
        dp[0] = 0;
        repeat (i,n) {
            repeat_reverse (j, sum_v-v[i]+1) {
                setmin(dp[j + v[i]], dp[j] + w[i]);
            }
        }
        repeat_reverse (j, sum_v+1) {
            if (dp[j] <= lim_w) {
                ans = j;
                break;
            }
        }
    }
    cout << ans << endl;
    return 0;
}
 
 
 
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