Submission #839815

#	Time	Username	Problem	Language	Result	Execution time	Memory
839815		nonono	Bootfall (IZhO17_bootfall)	C++14	100 / 100	293 ms	2756 KiB

bootfall

#include <bits/stdc++.h>
using namespace std;

const int mxN = 505;

int n, a[mxN];
int sum = 0;
int dp[mxN * mxN];
bool good[mxN * mxN];

void add(int x) {
    sum += x;
    for(int i = sum; i >= x; i --) dp[i] += dp[i - x];
}

void del(int x) {
    for(int i = x; i <= sum; i ++) dp[i] -= dp[i - x];
    sum -= x;
}

signed main() {
#define taskname ""

    if(fopen(taskname".inp", "r")) {
        freopen(taskname".inp", "r", stdin);
        freopen(taskname".out", "w", stdout);
    }

    cin.tie(0)->sync_with_stdio(0);
    
    cin >> n;
    
    dp[0] = 1;
    for(int i = 1; i <= n; i ++) {
        cin >> a[i];
        add(a[i]);
    }
    
    if(sum % 2 || !dp[sum / 2]) {
        return cout << 0, 0;
    }
    
    for(int i = 1; i <= sum; i ++) good[i] = true;
        
    for(int i = 1; i <= n; i ++) {
        del(a[i]);
        
        for(int j = 1; j <= sum + a[i]; j ++) {
            good[j] = (good[j] && (sum + j) % 2 == 0 && dp[(sum + j) / 2]);
        }
        
        add(a[i]);
    }
    
    vector<int> choose;
    for(int i = 1; i <= sum; i ++) if(good[i]) choose.push_back(i); 
    
    cout << choose.size() << "\n";
    
    for(int x : choose) cout << x << " ";
    
    return 0;
}

Compilation message (stderr)

bootfall.cpp: In function 'int main()':
bootfall.cpp:25:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |         freopen(taskname".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
bootfall.cpp:26:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |         freopen(taskname".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 6 / 6
• Subtask 2: 7 / 7
• Subtask 3: 15 / 15
• Subtask 4: 16 / 16
• Subtask 5: 21 / 21
• Subtask 6: 35 / 35