hdu 1199 Color the Ball 离散线段树-优快云博客

本文详细解析了使用C++解决「最长白色球序列」问题的算法，包括输入输出规范、核心算法步骤及代码实现，旨在帮助初学者理解并掌握该问题的求解策略。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

C - Color the Ball

Time Limit:1000MS Memory Limit:32768KB 64bit IO Format:%I64d & %I64u

Submit Status

Description

There are infinite balls in a line (numbered 1 2 3 ....), and initially all of them are paint black. Now Jim use a brush paint the balls, every time give two integers a b and follow by a char 'w' or 'b', 'w' denotes the ball from a to b are painted white, 'b' denotes that be painted black. You are ask to find the longest white ball sequence.

Input

First line is an integer N (<=2000), the times Jim paint, next N line contain a b c, c can be 'w' and 'b'.

There are multiple cases, process to the end of file.

Output

Two integers the left end of the longest white ball sequence and the right end of longest white ball sequence (If more than one output the small number one). All the input are less than 2^31-1. If no such sequence exists, output "Oh, my god".

Sample Input

      3 1 4 w 8 11 w 3 5 b 
    

Sample Output

    8 11 
  

 
    #include <cstdio>
#include <cmath>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <set>
#include <vector>
#include <sstream>
#include <queue>
#include <typeinfo>
#include <fstream>
typedef long long ll;
using namespace std;
//freopen("D.in","r",stdin);
//freopen("D.out","w",stdout);
#define sspeed ios_base::sync_with_stdio(0);cin.tie(0)

const int inf=0x7fffffff;   //无限大
char op[3];
struct interval
{
    int start,endn;
    bool operator < (const interval& b)const{
        if(start!=b.start)
            return start<b.start;
        else
            return endn<b.endn;
    }
};
interval val[20001];
void white(int a,int b,int& cnt)
{
    val[cnt].start=a;
    val[cnt].endn=b;
    cnt++;
}
void black(int a,int b,int& cnt)
{
    int tmp=cnt;
    for(int i=0;i<cnt;i++)
    {
        if(val[i].start<a)
        {
            if(val[i].endn>=a)
            {
                if(val[i].endn<=b)
                {
                    val[i].endn=a-1;
                }
                else
                {
                    val[tmp].start=b+1;
                    val[tmp].endn=val[i].endn;
                    tmp++;
                    val[i].endn=a-1;
                }
            }
        }
        else if(val[i].start<=b)
        {
            if(val[i].endn<=b)
            {
                val[i].start=0;
                val[i].endn=-1;
            }
            else
            {
                val[i].start=b+1;
            }
        }
    }
    cnt=tmp;
}
int solve(int cnt,int& index)
{
    sort(val,val+cnt);
    int maxn=val[0].endn-val[0].start+1;
    for(int i=1;i<cnt;i++)
    {
        if(val[i].start!=0)
        {
            if(val[i].start<=val[i-1].endn+1)
            {
                if(val[i-1].endn<=val[i].endn)
                {
                    val[i].start=val[i-1].start;
                }
                else
                {
                    val[i].start=val[i-1].start;
                    val[i].endn=val[i-1].endn;
                }
            }
            if(val[i].endn-val[i].start+1>maxn)
            {
                maxn=val[i].endn-val[i].start+1;
                index=i;
            }
        }
    }
    return maxn;
}
int main()
{
    int n,index,a,b,c;
    while(cin>>n)
    {
        int cnt=0;
        for(int i=0;i<n;i++)
        {
            scanf("%d%d%s",&a,&b,op);
            if(a>b)
            {
                swap(a,b);
            }
            if(op[0]=='w')
                white(a,b,cnt);
            else
                black(a,b,cnt);
        }
        index=0;
        if(solve(cnt,index))
        {
            cout<<val[index].start<<" "<<val[index].endn<<endl;
        }
        else
            cout<<"Oh, my god"<<endl;
    }
    return 0;
} 
   
 