HDOJ 4883 TIANKENG’s restaurant

題目：

TIANKENG’s restaurant

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 131072/65536 K (Java/Others)
Total Submission(s): 249 Accepted Submission(s): 125


Problem Description TIANKENG manages a restaurant after graduating from ZCMU, and tens of thousands of customers come to have meal because of its delicious dishes. Today n groups of customers come to enjoy their meal, and there are Xi persons in the ith group in sum. Assuming that each customer can own only one chair. Now we know the arriving time STi and departure time EDi of each group. Could you help TIANKENG calculate the minimum chairs he needs to prepare so that every customer can take a seat when arriving the restaurant?
Input The first line contains a positive integer T(T<=100), standing for T test cases in all.

Each cases has a positive integer n(1<=n<=10000), which means n groups of customer. Then following n lines, each line there is a positive integer Xi(1<=Xi<=100), referring to the sum of the number of the ith group people, and the arriving time STi and departure time Edi(the time format is hh:mm, 0<=hh<24, 0<=mm<60), Given that the arriving time must be earlier than the departure time.

Pay attention that when a group of people arrive at the restaurant as soon as a group of people leaves from the restaurant, then the arriving group can be arranged to take their seats if the seats are enough.

Output For each test case, output the minimum number of chair that TIANKENG needs to prepare.
Sample Input

2
2
6 08:00 09:00
5 08:59 09:59
2
6 08:00 09:00
5 09:00 10:00

Sample Output

11
6

解題思路：

轉換為RMQ問題，1天24h，1440min；a[i]表示第i分鐘的人數,n表示時間[t1,t2)之間來的人數，對這個區間內的a[i]+n,最後求的是a[i]的最大值。

解法1：模擬

#include 
#include 
#include 
using namespace std;

#define clr(a) memset(a, 0, sizeof(a))
#define rep(i,s,t) for(int i = s; i <= t; ++i)
#define per(i,s,t) for(int i = s; i >= t; --i)

const int MAXN = 1450;
int t, n, a[MAXN];

int main()
{
    scanf("%d", &t);
    while(t--)
    {
        clr(a);
        scanf("%d", &n);
        int num, h1, m1, h2, m2;
        rep(i,0,n-1)
        {
            scanf("%d%d:%d%d:%d", &num, &h1, &m1, &h2, &m2);
            int s1 = h1 * 60 + m1, s2 = h2 * 60 + m2;
            rep(j,s1,s2-1) a[j] += num;
        }
        int ans = -1;
        rep(i,0,MAXN-1) ans = max(ans,a[i]);
        printf("%d\n", ans);
    }
    return 0;
}

解法2：線段樹（ZKW）

#include 
#include 
#include 
using namespace std;

#define clr(a) memset(a, 0, sizeof(a))
#define rep(i,s,t) for(int i = s; i <= t; ++i)
#define per(i,s,t) for(int i = s, i >= t; --i)

const int M = 1<<11, MAXN = 1440;
int icase, n, a[M << 1];


void Add_x(int s, int t, int x)
{
    int b = 0;
    for(s=s+M-1, t=t+M+1; s^t^1; s>>=1, t>>=1)
    {
        if(~s&1) a[s^1] += x;
        if( t&1) a[t^1] += x;
        b = max(a[s], a[s^1]), a[s]-=b, a[s^1]-=b, a[s>>1]+=b;
        b = max(a[t], a[t^1]), a[t]-=b, a[t^1]-=b, a[t>>1]+=b;
      //  printf("%d %d %d %d\n", s, t, a[s^1], a[t^1]);
    }
    for( ; s > 1; s>>=1)
    b = max(a[s], a[s^1]), a[s]-=b, a[s^1]-=b, a[s>>1]+=b;
}

int Max(int s, int t)
{
    int lans = 0, rans = 0, ans = 0;
    for(s=s+M-1,t=t+M+1; s^t^1; s>>=1, t>>=1)
    {
        lans+=a[s], rans+=a[t];
        if(~s&1) lans = max(lans, a[s^1]);
        if( t&1) rans = max(rans, a[t^1]);
     //   printf("%d %d %d %d\n", s, t, lans, rans);
    }
    ans = max(lans+a[s], rans+a[t]);
    while(s>1) ans+=a[s>>=1];
    return ans;
}

void show()
{
    for(int i = 0; i < M; i++)
        printf("%d ", a[i]);
    printf("\n");
}

int main()
{
    scanf("%d", &icase);
    while(icase--)
    {
        scanf("%d", &n); clr(a);
        int num, h1, m1, h2, m2;
        for(int i = 0; i < n; ++i)
        {
            scanf("%d%d:%d%d:%d", &num, &h1, &m1, &h2, &m2);
            int s1 = h1 * 60 + m1, s2 = h2 * 60 + m2;
            Add_x(1+s1, s2, num);
        }
    //    show();
        printf("%d\n", Max(1,1440));
    }
    return 0;
}