HDU2795 Billboard

线段树单点更新~

建立线段树存储区间内的最大剩余宽度，优先询问左子树~

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int maxn=1e6+14;
struct node {
    int l,r,sum;
}segTree[maxn*4];
int h,w,n;
void build (int i,int l,int r) {
    segTree[i].l=l;
    segTree[i].r=r;
    segTree[i].sum=w;
    if (l==r) return;
    int mid=(l+r)>>1;
    build(i<<1,l,mid);
    build(i<<1|1,mid+1,r);
    segTree[i].sum=max(segTree[i<<1].sum,segTree[i<<1|1].sum);
}
int query (int i,int x) {
    if (segTree[i].l==segTree[i].r) {
        segTree[i].sum-=x;
        return segTree[i].l;
    }
    int mid=(segTree[i].l+segTree[i].r)>>1;
    int ans;
    if (segTree[i<<1].sum>=x) ans=query(i<<1,x);
    else ans=query(i<<1|1,x);
    segTree[i].sum=max(segTree[i<<1].sum,segTree[i<<1|1].sum);
    return ans;
}
int main () {
    while (~scanf("%d %d %d",&h,&w,&n)) {
        h=min(h,n);
        build(1,1,h);
        int x;
        while (n--) {
            scanf ("%d",&x);
            if (segTree[1].sum<x) printf ("-1\n");
            else printf ("%d\n",query(1,x));
        }
    }
    return 0;
}