hdu 2795 线段树

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2795

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <queue>
#include <vector>

#define maxn 222222
#define lson l,mid,u<<1
#define rson mid+1,r,u<<1|1
using namespace std;

const int INF = 0x3f3f3f;
int h,w,n;
int seg[maxn<<2];
int row;

int Push_UP(int u){
    seg[u] = max(seg[u<<1],seg[u<<1|1]);  //****这个地方 u<<1|1 不能换为 u << 1 +1 
}
void build(int l,int r,int u){
    if(l == r){
         seg[u] = w;
         return;
    }
    int mid = (l + r)>>1; 
    build(lson);
    build(rson);
    Push_UP(u);
}
void Update(int loc,int num,int l,int r,int u){
    if(l == r){  // 这个地方要注意！！ 
        seg[u] -= num;  
        return;
    }
    int mid = (l + r)/2; 
    if(loc <= mid) Update(loc,num,lson);
    else           Update(loc,num,rson);
    Push_UP(u);
}

int Query(int num,int l,int r,int u){
    if(seg[u] < num) return -1;
    
    if(l == r && seg[u] >= num){
        return l;
    }
    int ret = 0;  
    int mid = (l + r)/2;
    ret = Query(num,lson);
    if(ret != -1) return ret;
    else          return Query(num,rson);    
}
int main()
{
    //if(freopen("input.txt","r",stdin)== NULL)  {printf("Error
"); exit(0);}
    while(cin>>h>>w>>n){
        if(h > n) h = n;
        build(1,h,1); 
        while(n--){
            int a;     
            scanf("%d
",&a);
            row = Query(a,1,h,1);
            if(row == -1) printf("-1
");
            else{
                Update(row,a,1,h,1);
                printf("%d
",row);
            }
        }
    }
}

参考别人的改进版：

#include <cstdio>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <cstring>
#include <queue>
#include <vector>

#define maxn 222222
#define lson l,mid,u<<1
#define rson mid+1,r,u<<1|1
using namespace std;

const int INF = 0x3f3f3f;
int h,w,n;
int seg[maxn<<2];


int Push_UP(int u){
    seg[u] = max(seg[u<<1],seg[u<<1|1]);  //****这个地方 u<<1|1 不能换为 u << 1 +1 
}
void build(int l,int r,int u){
    if(l == r){
         seg[u] = w;
         return;
    }
    int mid = (l + r)>>1; 
    build(lson);
    build(rson);
    Push_UP(u);
}
int Query(int num,int l,int r,int u){
    if(l == r ){
        seg[u] -= num;
        return l;
    }
    int ret = 0;  
    int mid = (l + r)/2;
    if(seg[u<<1] >= num)     ret = Query(num,lson);
    else                     ret = Query(num,rson);
    Push_UP(u);    
    return ret;
}
int main()
{
    //if(freopen("input.txt","r",stdin)== NULL)  {printf("Error
"); exit(0);}
    while(cin>>h>>w>>n){
        if(h > n) h = n;
        build(1,h,1); 
        while(n--){    
            int num; 
            scanf("%d
",&num);
            if(seg[1]<num)  printf("-1
");
            else          printf("%d
",Query(num,1,h,1));
        }
    }
}