CCF 201812-2 小明放学

#include <iostream>
#include <bits/stdc++.h>
#include <string>

using namespace std;

int r,y,g;

void change(long long int sum,int &k,int &t)//最开始显示为t秒，sum秒后为什么状态，此时为k灯
{
    sum%=(r+y+g);///不加此句会超时
    if(k==0)
        return;
    if(sum-t<0)
    {
        t-=sum;
        return;
    }
    else
    {
        sum-=t;
        if(k==1)
            k=3;
        else if(k==3)
            k=2;
        else if(k==2)
            k=1;
    }
    while(sum>=0)//1--》3--》2
    {
        switch (k)
        {
        case 1:
            if(sum-r<0)
            {
                t=r-sum;
                return;
            }
            else
            {
                if(k==1)
                    k=3;
                else if(k==3)
                    k=2;
                else if(k==2)
                    k=1;
                sum-=r;
            }
            break;
        case 2:
            if(sum-y<0)
            {
                t=y-sum;
                return;
            }
            else
            {
                if(k==1)
                    k=3;
                else if(k==3)
                    k=2;
                else if(k==2)
                    k=1;
                sum-=y;
            }
            break;
        case 3:
            if(sum-g<0)
            {
                t=g-sum;
                return;
            }
            else
            {
                if(k==1)
                    k=3;
                else if(k==3)
                    k=2;
                else if(k==2)
                    k=1;
                sum-=g;
            }
            break;
        }
    }
}

int main()
{
    cin>>r>>y>>g;
    int n;
    cin>>n;
    long long int sum=0;
    while(n--)
    {
        int k,t;
        cin>>k>>t;
        change(sum,k,t);
        switch (k)
        {
        case 0:
            sum+=t;
            break;
        case 1:
            sum+=t;
            break;
        case 2:
            sum+=(t+r);
            break;
        case 3:
            break;
        }
    }
    cout<<sum<<endl;
}