HDU 2665 Kth number(归并树写法)

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#include<cstdio>#include<string>#define maxn 100001int n,m,num[maxn],tr[18][maxn],s[maxn],e[maxn],h[maxn],top;void merge(int height,int a,int b){    if (a==b){        tr[height][a]=num[a];        return;    }    int mid=(a+b)>>1;    merge(height+1,a,mid);    merge(height+1,mid+1,b);    int i=a,j=mid+1,k=a;    while (i<=mid&&j<=b)        if (tr[height+1][i]<tr[height+1][j])  tr[height][k++]=tr[height+1][i++];        else tr[height][k++]=tr[height+1][j++];    while (i<=mid) tr[height][k++]=tr[height+1][i++];    while (j<=b) tr[height][k++]=tr[height+1][j++];    return;}void get(int l,int r,int a,int b,int height){    if (l==a&&r==b){        s[top]=l; e[top]=r; h[top++]=height;        return;    }    int mid=(l+r)>>1;    if (b<=mid) return get(l,mid,a,b,height+1);    else if (a>mid) return get(mid+1,r,a,b,height+1);    else{        get(l,mid,a,mid,height+1);        get(mid+1,r,mid+1,b,height+1);    }    return;}int search(int x){    int i,k=0;    for (i=0;i<top;i++){        int l=s[i],r=e[i],height=h[i];        while (l<=r){            int mid=(l+r)>>1;            if (tr[height][mid]<=x){                k+=mid-l+1;                l=mid+1;            }            else  r=mid-1;        }    }    return k;}void find(int k){    int maxi=n-1,mini=0;    while(mini<maxi){        int mid=(mini+maxi)>>1;        int res=search(tr[0][mid]);        if (res<k) mini=mid+1;        else maxi=mid;    }    printf("%d\n",tr[0][mini]);    return;}void solve(){    scanf("%d %d",&n,&m);    for(int i=0;i<n;i++) scanf("%d",&num[i]);    merge(0,0,n-1);    for(int i=0;i<m;i++){        int a,b,k;        scanf("%d %d %d",&a,&b,&k);        top=0;        get(0,n-1,a-1,b-1,0);        find(k);    }    return;}int main(){    int test;    scanf("%d",&test);    while (test--)        solve();}
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