比赛 树状数组练习 评测结果 AAAAAAAAAA
题目名称 奶牛排序 最终得分 100
用户昵称 LikableP 运行时间 0.152 s
代码语言 C++ 内存使用 2.46 MiB
提交时间 2025-06-11 20:28:48
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#include <cstdio>
#include <cstring>
typedef long long ll;
#define isdigit(ch) ((ch) >= '0' && (ch) <= '9')
#define lowbit(x) (x & -x)
#define max(__a, __b) [&](int _a, int _b) {return _a > _b ? _a : _b;} ((__a), (__b))

template <typename T> T read() {
    T res = 0, f = 1;
    char ch = getchar();
    for (; !isdigit(ch); ch = getchar()) if (ch == '-') f = -1;
    for (; isdigit(ch); ch = getchar()) res = (res << 3) + (res << 1) + (ch ^ 48);
    return res * f;
}

template <typename T> void write(T x, char ed = '\n') {
    if (x < 0) putchar('-'), x = -x;
    static int sta[16], top = 0;
    do {
        sta[++top] = x % 10;
        x /= 10;
    } while(x);
    while (top) {
        putchar(sta[top--] ^ 48);
    }
    putchar(ed);
}

const int MAXN = 1e5 + 10;

int n;
int maxx = -1;
ll ans;
int a[MAXN], l[MAXN], r[MAXN];
int tree[MAXN];

void add(int x, int y) {
    for (; x <= maxx; x += lowbit(x)) tree[x] += y;
} 

int ask(int x) {
    int res = 0;
    for (; x; x -= lowbit(x)) res += tree[x];
    return res;
}

int main() {
    freopen("cow.in", "r", stdin);
    freopen("cow.out", "w", stdout);
    n = read<int>();
    for (int i = 1; i <= n; ++i) {
        a[i] = read<int>();
        maxx = max(maxx, a[i]);
    }
    for (int i = 1; i <= n; ++i) {
        l[i] = ask(maxx) - ask(a[i]);
        add(a[i], 1);
    }
    memset(tree, 0, sizeof tree);
    for (int i = n; i >= 1; --i) {
        r[i] = ask(a[i] - 1);
        add(a[i], 1);
    }
    for (int i = 1; i <= n; ++i) {
        ans += (ll)(l[i] + r[i]) * a[i];
    }
    write(ans);
    return 0;
}