poj 3253 最小堆 优先队列 哈夫曼树

import java.io.*;

class Heap {
private final int maxn = 50010;
int[] data;
int r;

Heap() {
data = new int[maxn];
r = 0;
}

public int size() {
return r;
}

void swap(int a, int b) {
int tmp = data[a];
data[a] = data[b];
data[b] = tmp;
}

void up(int p) {
if (!(p > 0))
return;
int q = p >> 1;
if (data[p] < data[q]) {
swap(p, q);
up(q);
}
}

void down(int p) {
int q;
if ((p << 1) >= r)
return;
else if ((p << 1) == r - 1) {
q = p << 1;
} else {
q = (data[p << 1] < data[p << 1 | 1] ? p << 1 : p << 1 | 1);
}
if (data[p] > data[q]) {
swap(p, q);
down(q);
}
}

void push(int n) {
data[r++] = n;
up(r - 1);
}

int pop() {
int res = data[0];
swap(0, r - 1);
r--;
down(0);
return res;
}

int top() {
return data[0];
}

}

public class Main {
private static long solve(int[] a) {
Heap hp = new Heap();
int n = a[0], l1, l2;
long res = 0;
for (int i = 1; i <= n; i++)
hp.push(a[i]);
// hp.print();
while (hp.size() > 1) {
l1 = hp.pop();
l2 = hp.pop();
res += (long) (l1 + l2);
hp.push(l1 + l2);
}
return res;
}

public static void main(String[] args) throws IOException {
StreamTokenizer in = new StreamTokenizer(new BufferedReader(
new InputStreamReader(System.in)));
PrintWriter out = new PrintWriter(System.out);
while (in.nextToken() != StreamTokenizer.TT_EOF) {
int n = (int) in.nval;
int[] a = new int[n + 1];
a[0] = n;
for (int i = 1; i <= n; i++) {
in.nextToken();
a[i] = (int) in.nval;
}

if (n > 1)
out.println(solve(a));
else
out.println(a[1]);
out.flush();
}
out.close();
}
}