标签:
Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 662    Accepted Submission(s): 329
#include<stdio.h>
#include<algorithm>
#include<string.h>
#include<math.h>
#include<string>
#include<iostream>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#include<set>
using namespace std;
typedef long long LL;
#define mid (L+R)/2
#define lson rt*2,L,mid
#define rson rt*2+1,mid+1,R
#pragma comment(linker, "/STACK:102400000,102400000")
const int maxn = 1e5+300;
const int INF = 0x3f3f3f3f;
typedef long long  LL;
typedef unsigned long long ULL;
struct Seg{
    LL val, Min, Max;
    int idmin, idmax;
}segs[maxn*4];
LL a[maxn];
LL ans[maxn];
int n;
void PushUP(int rt){
    segs[rt].Max = max(segs[rt*2].Max,segs[rt*2+1].Max);
    segs[rt].Min = min(segs[rt*2].Min,segs[rt*2+1].Min);
    if(segs[rt*2].Max > segs[rt*2+1].Max)
        segs[rt].idmax = segs[rt*2].idmax;
    else segs[rt].idmax = segs[rt*2+1].idmax;
    if(segs[rt*2].Min < segs[rt*2+1].Min)
        segs[rt].idmin = segs[rt*2].idmin;
    else segs[rt].idmin = segs[rt*2+1].idmin;
}
void buildtree(int rt,int L,int R){
    if(L == R){
        segs[rt].val = a[L];
        segs[rt].idmax = segs[rt].idmin = L;
        segs[rt].Min = segs[rt].Max = a[L];
        return;
    }
    buildtree(lson);
    buildtree(rson);
    PushUP(rt);
}
int querymin(int rt,int L,int R,int l_ran,int r_ran){
    if(l_ran<=L&&R<=r_ran){
        return segs[rt].idmin;
    }
    int id = 0;
    if(l_ran <= mid){
        id = querymin(lson,l_ran,r_ran);
    }
    if(r_ran > mid){
        int tid = querymin(rson,l_ran,r_ran);
        if(id != 0){
            if(a[id] > a[tid])
                id = tid;
        }else{
            id = tid;
        }
    }
    return id;
}
int querymax(int rt,int L,int R,int l_ran,int r_ran){
    if(l_ran<=L&&R<=r_ran){
        return segs[rt].idmax;
    }
    int id = 0;
    if(l_ran <= mid){
        id = querymax(lson,l_ran,r_ran);
    }
    if(r_ran > mid){
        int tid = querymax(rson,l_ran,r_ran);
        if(id != 0){
            if(a[id] < a[tid])
                id = tid;
        }else{
            id = tid;
        }
    }
    return id;
}
void dfs(int l, int r){
    if(l > r) return;
    int idmin, idmax;
    idmin = querymin(1,1,n,l,r);
    idmax= querymax(1,1,n,l,r);
    if(idmax < idmin)
        swap(idmin,idmax);
    LL tmp = a[idmax]*a[idmin];
    for(int i = idmax-idmin+1; i <= r-l+1; i++){
        ans[i] = max(ans[i], tmp);
    }
    if(a[idmax] > a[idmin]){
        dfs(l,idmin-1);
        dfs(idmin+1,r);
    }else{
        dfs(l,idmax-1);
        dfs(idmax+1,r);
    }
}
int main(){
    while(scanf("%d",&n)!=EOF){
        LL ret = 0;
        for(int i = 1; i <= n; i++){
            scanf("%lld",&a[i]);
        }
        buildtree(1,1,n);
        for(int i = 1; i <= n; ++i){
            ans[i] = 1;
        }
        dfs(1,n);
        for(int i = 1; i <= n; i++){
            printf("%lld\n",ans[i]);
        }
    }
    return 0;
}
/*
5
5 1 2 4 4
*/
HDU 5696 ——区间的价值——————【线段树、快排思想】
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原文地址:http://www.cnblogs.com/chengsheng/p/5529783.html