Submission #701355

#	Time	Username	Problem	Language	Result	Execution time	Memory
701355		tgp072	Knapsack (NOI18_knapsack)	C++14	100 / 100	55 ms	2964 KiB

knapsack

//#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <math.h>
#include <set>
#include <map>
#include <string>
#include <tuple>
#include <numeric>
#include <climits>
#include <bitset>
#include <iomanip>
#include <random>
#include <ctime>

using namespace std;

//change the long long to int if you need to save memory/time really badly
typedef long long ll;

//Comment this define when working on interactive problems
#define endl "\n"
#define sqrt(n) sqrt((long double) n)

const ll MAXN = 2e5 + 5;
const ll ZER = 0;
const ll ONE = 1;
const ll INF = LLONG_MAX;
const ll MOD = 1e9 + 7;

ll min(ll a, ll b) {
    if (a < b) {
        return a;
    } else {
        return b;
    }
}
 
ll max(ll a, ll b) {
    if (a > b) {
        return a;
    } else {
        return b;
    }
}

ll mod(ll num) {
    return (num >= MOD ? num % MOD : num);
}

ll __gcd(ll a, ll b) {
    if (b == 0) {
        return a;
    }
    
    if (a == 0) {
        return b;
    }
    
    if (a < b) {
        swap(a, b);
    }
    
    return __gcd(b, a % b);
}

ll __lcm(ll a, ll b) {
    ll prod = a*b;
    return prod/__gcd(a, b);
}

ll powmod(ll a, ll b){
    a %= MOD;
    if (a == 0) return 0;
    ll product = 1;
    while(b > 0){
        if (b&1){    // you can also use b % 2 == 1
            product *= a;
            product %= MOD;
            --b;
        }
        a *= a;
        a %= MOD;
        b /= 2;    // you can also use b >> 1
    }
    return product;
}


//calculates the inverse of a number mod MOD
ll inv(ll a) {
    return powmod(a, MOD - 2);
}

void solve(ll ca)
{
    ll s, n;
    cin >> s >> n;
    
    vector<pair<ll, ll>> items[s+1]; //list of items with the same weight, sorted by the value
    
    for (ll i = 0; i < n; i++) {
        ll v, w, k;
        cin >> v >> w >> k;
        
        items[w].push_back({v, k});
    }
    
    vector<ll> weights[s+1];
    for (ll i = 0; i <= s; i++) {
        if (items[i].size() == 0) {
            continue;
        }
        
        sort(items[i].begin(), items[i].end(), greater<>());
        ll cur = 0;
        for (ll j = 0; j < items[i].size(); j++) {
            ll k = 0;
            while (cur+i <= s && k < items[i][j].second) {
                weights[i].push_back(items[i][j].first);
                k++;
                cur += i;
            }
            
            if (cur+i > s) {
                break;
            }
        }
    }

    ll dp[s+1]; //dp[i] is the maximum value you can get with a weight of i
    for (ll i = 0; i <= s; i++) {
        dp[i] = -1;
    }
    dp[0] = 0;
    
    for (ll we = 0; we <= s; we++) {
        if (weights[we].size() == 0) {
            continue;
        }
        for (ll i = s; i >= 0; i--) {
            if (dp[i] != -1) {
                ll cur = i; ll csum = 0; ll ind = 0;
                while (cur+we <= s && ind < weights[we].size()) {
                    dp[cur+we] = max(dp[cur+we], dp[i]+csum+weights[we][ind]);
                    csum += weights[we][ind];
                    cur += we;
                    ind++;
                }
            }
        }
    }
    
    ll ans = 0;
    for (ll i = 0; i <= s; i++) {
        ans = max(ans, dp[i]);
    }
    
    cout << ans << endl;
    
    return;
}

int main()
{
    //mt19937 rng(0);
    
    //Fast IO
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    /*
    freopen("feast.in", "r", stdin);
    freopen("feast.out", "w", stdout);
    */
    
    ll t = 1;
    //cin >> t;

    ll co = 1;
    while (t--) {
        solve(co);
        ++co;
    }
}

//Always write your algorithm down on a piece of paper and question EACH and EVERY step if you aren't able to find an implementation mistake in your code.

Compilation message (stderr)

knapsack.cpp: In function 'void solve(ll)':
knapsack.cpp:123:26: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  123 |         for (ll j = 0; j < items[i].size(); j++) {
      |                        ~~^~~~~~~~~~~~~~~~~
knapsack.cpp:150:43: warning: comparison of integer expressions of different signedness: 'll' {aka 'long long int'} and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  150 |                 while (cur+we <= s && ind < weights[we].size()) {
      |                                       ~~~~^~~~~~~~~~~~~~~~~~~~

• Subtask 1: 12 / 12
• Subtask 2: 17 / 17
• Subtask 3: 20 / 20
• Subtask 4: 24 / 24
• Subtask 5: 27 / 27