0分求助qwq

神秘族首领 @ 2023-07-26 10:38:13

#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;

typedef long long ll;
ll a[500010];
ll n;
int ans = 0;

void merge(ll left, ll right) {
    ll mid = (left + right) / 2;
    ll l[n + 2];
    ll r[n + 2];
    for (ll i = left; i <= mid; i++) {
        l[i] = a[i];
    }
    for (ll i = mid + 1; i <= right; i++) {
        r[i] = a[i];
    }
    l[mid + 1] = 99999999;
    r[right + 1] = 99999999;
    ll templ = left;
    ll tempr = mid + 1;
    for (ll i = left; i <= right; i++) {
        if (l[templ] <= r[tempr]) {
            a[i] = l[templ];
            //ans += templ - left + tempr - right;
            templ++;
        } else {
            a[i] = r[tempr];
            //ans++;
            ans += mid - templ + 1;
            tempr++;
        }
    }
}

void mergesort(ll left, ll right) {
    ll mid = (left + right) / 2;
    if (left < right) {
        mergesort(left, mid);
        mergesort(mid + 1, right);
        merge(left, right);
    }
}

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    mergesort(1, n);
//  for (int i = 1; i <= n; i++)
//      cout << a[i] << " ";
    //cout << endl;
    cout << ans ;
    return 0;
}

by 神秘族首领 @ 2023-07-26 11:23:55

没事了，测试数据应该都是至少1000个数以上，并且每个数很大很大

by 神秘族首领 @ 2023-07-26 11:24:16

l[mid + 1] = 99999999; r[right + 1] = 99999999; 这两行开的太小了

by 神秘族首领 @ 2023-07-26 11:24:47

#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;

typedef long long ll;
ll a[500010];
ll n;
ll ans = 0;

void merge(ll left, ll right) {
    ll mid = (left + right) / 2;
    ll l[n + 2];
    ll r[n + 2];
    for (ll i = left; i <= mid; i++) {
        l[i] = a[i];
    }
    for (ll i = mid + 1; i <= right; i++) {
        r[i] = a[i];
    }
    l[mid + 1] = 1e15;
    r[right + 1] = 1e15;
    ll templ = left;
    ll tempr = mid + 1;
    for (ll i = left; i <= right; i++) {
        if (l[templ] <= r[tempr]) {
            a[i] = l[templ];
            //ans += templ - left + tempr - right;
            templ++;
        } else {
            a[i] = r[tempr];
            //ans++;
            ans += mid - templ + 1;
            tempr++;
        }
    }
}

void mergesort(ll left, ll right) {
    ll mid = (left + right) / 2;
    if (left < right) {
        mergesort(left, mid);
        mergesort(mid + 1, right);
        merge(left, right);
    }
}

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    mergesort(1, n);
//  for (int i = 1; i <= n; i++)
//      cout << a[i] << " ";
    //cout << endl;
    cout << ans ;
    return 0;
}

这样就能过了