[Usaco2015 DEC] Counting Haybales

[题目链接]

         https://www.lydsy.com/JudgeOnline/problem.php?id=4392

[算法]

         线段树

         时间复杂度 ： O(MlogN)

[代码]

        

#include<bits/stdc++.h>
using namespace std;
#define MAXN 200010
typedef long long LL;

int n , m;
LL a[MAXN];

struct SegmentTree
{
    struct Node
    {
        int l , r;
        LL sum , val;
        LL tag;
    } Tree[MAXN << 2];
    inline void build(int index , int l , int r)
    {
        Tree[index].l = l;
        Tree[index].r = r;
        Tree[index].tag = 0;
        if (l == r)
        {
            Tree[index].sum = Tree[index].val = a[l];
            return;
        }
        int mid = (l + r) >> 1;
        build(index << 1 , l , mid);
        build(index << 1 | 1 , mid + 1 , r);
        update(index);
    }
    inline void update(int index)
    {
        Tree[index].sum = Tree[index << 1].sum + Tree[index << 1 | 1].sum;
        Tree[index].val = min(Tree[index << 1].val , Tree[index << 1 | 1].val);
    }
    inline void pushdown(int index)
    {
        int l = Tree[index].l , r = Tree[index].r;
        int mid = (l + r) >> 1;
        Tree[index << 1].sum += Tree[index].tag * (mid - l + 1);
        Tree[index << 1 | 1].sum += Tree[index].tag * (r - mid);
        Tree[index << 1].val += Tree[index].tag;
        Tree[index << 1 | 1].val += Tree[index].tag;
        Tree[index << 1].tag += Tree[index].tag;
        Tree[index << 1 | 1].tag += Tree[index].tag;
        Tree[index].tag = 0;
    }
    inline void modify(int index , int l , int r , LL value)
    {
        if (Tree[index].l == l && Tree[index].r == r)
        {
            Tree[index].sum += (r - l + 1) * value;
            Tree[index].val += value;
            Tree[index].tag += value;
            return;
        }
        pushdown(index);
        int mid = (Tree[index].l + Tree[index].r) >> 1;
        if (mid >= r) modify(index << 1 , l , r , value);
        else if (mid + 1 <= l) modify(index << 1 | 1 , l , r , value);
        else
        {
            modify(index << 1 , l , mid , value);
            modify(index << 1 | 1 , mid + 1 , r , value);
        }
        update(index);
    }
    inline LL query_sum(int index , int l , int r)
    {
        if (Tree[index].l == l && Tree[index].r == r) return Tree[index].sum;
        pushdown(index);
        int mid = (Tree[index].l + Tree[index].r) >> 1;
        if (mid >= r) return query_sum(index << 1 , l , r);
        else if (mid + 1 <= l) return query_sum(index << 1 | 1 , l , r);
        else return query_sum(index << 1 , l , mid) + query_sum(index << 1 | 1 , mid + 1 , r);
    }
    inline LL query_min(int index , int l , int r)
    {
        if (Tree[index].l == l && Tree[index].r == r) return Tree[index].val;
        pushdown(index);
        int mid = (Tree[index].l + Tree[index].r) >> 1;
        if (mid >= r) return query_min(index << 1 , l , r);
        else if (mid + 1 <= l) return query_min(index << 1 | 1 , l , r);
        else return min(query_min(index << 1 , l , mid) , query_min(index << 1 | 1 , mid + 1 , r));
    }
} T;

template <typename T> inline void chkmax(T &x , T y) { x = max(x , y); }
template <typename T> inline void chkmin(T &x , T y) { x = min(x , y); }
template <typename T> inline void read(T &x)
{
    T f = 1; x = 0;
    char c = getchar();
    for (; !isdigit(c); c = getchar()) if (c == '-') f = -f;
    for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + c - '0';
    x *= f;
}

int main()
{
    
    read(n); read(m);
    for (int i = 1; i <= n; i++) read(a[i]);
    T.build(1 , 1 , n);
    while (m--)
    {
        char op[5];
        scanf("%s",op);
        if (op[0] == 'P')
        {
            int l , r;
            LL x;
            read(l); read(r); read(x);
            T.modify(1 , l , r , x);    
        }
        if (op[0] == 'S')
        {
            int l , r;
            read(l); read(r);
            printf("%lld\n" , T.query_sum(1 , l ,r));
        }
        if (op[0] == 'M')
        {
            int l , r;
            read(l); read(r);
            printf("%lld\n", T.query_min(1 , l , r));
        }
    }
    
    return 0;
}