2.14

哈夫曼树：

最小堆：

https://www.acwing.com/problem/content/150/

合并果子

拓展题：282，2889

c写法：

#include<iostream>
using namespace std;
const int N = 10010;
int n;
int heap[N];

void down(int x){
    int t = x;
    if(2*x <= n && heap[2*x] < heap[t]) t = 2*x;
    if(2*x + 1 <= n && heap[2*x + 1] < heap[t]) t = 2*x + 1;
    if(heap[t] < heap[x]){
        swap(heap[t], heap[x]);
        down(t);
    }
}
void up(int x){
    while(x > 1 && heap[x/2] > heap[x]){
        swap(heap[x], heap[x/2]);
        x >>= 1;
    }
}
int main(){
    cin >> n;
    for(int i = 1; i <= n; i++) cin >> heap[i];

    for(int i = n/2; i >= 1; i--) down(i);

    int res = 0;
    while(n > 1){
        int a = heap[1];
        heap[1] = heap[n--];
        down(1);

        int b = heap[1];
        heap[1] = heap[n--];
        down(1);

        res += a + b;
        heap[++n] = a + b;
        up(n);
    }

    cout << res << endl;
}

View Code

c++写法：stl大法

#include<bits/stdc++.h>
using namespace std;
int n,ans,a[10001];
bool cmp(int x,int y){return x>y;}
int main(){
    cin>>n; for(int i=0;i<n;i++) cin>>a[i];
    make_heap(a,a+n,cmp);
    for(int i=n;i>1;i--){
        pop_heap(a,a+i,cmp); pop_heap(a,a+i-1,cmp);
        a[i-2]+=a[i-1]; ans+=a[i-2];
        push_heap(a,a+i-1,cmp);
    }
    cout<<ans<<endl;
    return 0;
}

View Code

桶排+队列：

#include<bits/stdc++.h>
using namespace std;
int n,a,cnt[20009],Max;
long long ans;
queue<int> q1,q2;
int main(){
    cin>>n;
    for(int i=1;i<=n;++i){scanf("%d",&a);Max=max(a,Max),cnt[a]++;}
    for(int i=1;i<=Max;++i)
        while(cnt[i]--)q1.push(i);
    for(int i=1,x1,x2;i<n;++i){
        if(q2.empty()||!q1.empty()&&q1.front()<q2.front()){x1=q1.front();q1.pop();}//我是个沙茶，之前把q1.empty()写成了q1.front()
        else{x1=q2.front();q2.pop();}
        if(q2.empty()||!q1.empty()&&q1.front()<q2.front()){x2=q1.front();q1.pop();}
        else{x2=q2.front();q2.pop();}
        q2.push(x1+x2);ans+=x1+x2;
    }
    cout<<ans<<endl;
    return 0;
}

View Code

 

标签：int,down,--,heap,ans,2.14,cmp
来源： https://www.cnblogs.com/chouhui/p/14401441.html