SDUT 2021 summer team contest 11th

https://vjudge.net/contest/454997#problem/B

B

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#include <iostream>
#include <algorithm>
#include <cstring>
#include <map>
#include <vector>
using namespace std;
#define int long long 
typedef long long ll;
int n;
const int N = 5e3 + 7;
int a[N];
int dp[N][N];
signed main() {
    scanf("%lld",&n);
    for ( int i = 1; i <= n; i ++) scanf("%lld", a + i);
    sort(a + 1,a + 1 + n);
    int ans = 0;
    for (int i = 2; i < n; i ++ ) {
        for (int j = 1 ; j < i;j ++ ) {
            int po = lower_bound(a + 1,a + 1 + n,2*a[i] - a[j]) - a;
            if (a[po] + a[j] == 2*a[i])
            dp[po][i] = max(dp[i][j] + 1,dp[po][i]);
        }
    }
    for (int i = 1; i <= n; i ++ )
        for (int j = 1; j <= n; j ++ ) ans = max(ans, dp[i][j]);
    cout << ans + 2 << endl;
}

D 待补

G

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#include <iostream>
#include <algorithm>
#include <cstring>
#include <map>
#include <vector>
using namespace std;
#define int long long 
typedef long long ll;
int n;
const int N = 1e5 + 7;
int tr[N],a[N],tr2[N];
ll L[N],R[N],R2[N],L2[N];
ll ask(int x) {
    ll ans = 0;
    for (; x ;x -= x &-x) ans += tr[x];
    return ans;
}
void add(int x,int v) {
    for (; x <= N; x += x &-x) tr[x] += v;
}
signed main() {
    int maxc = 0,minc = 0x3f3f3f3f;
    cin >> n;for (int i = 1; i <= n ; i ++ ) {
        int x;
        scanf("%lld", &x);
        a[i] = x;
        maxc = max(maxc,x);
        minc = min(minc,x);
    }
    for (int i = n ; i >= 1 ;i -- ) {
        int x = a[i];
        ll res = ask(x - 1);
        R[i] = res;
        R2[i] = max(0ll,ask(100000) - ask(x));
        add(x,1);
    }
    memset(tr,0,sizeof tr);
    for (int i = 1; i <= n; i ++ ) {
        int x = a[i];
        ll res = ask(x - 1);
        L[i] = res;
        L2[i] = max(ask(100000) - ask(x),0ll);
        add(x,1);
    }
    int mincc = 0x3f3f3f3f, sum= 0;
    int ans = 0;
    for (int i = 1; i <= n; i ++ ) {
        //cout << a[i] << ' ' << L2[i] << ' ' << R2[i] << endl;
        ans += min(L2[i],R2[i]);
    }
    cout << ans << endl;
}