頭が働いていなかったので30~31行目と32行目の違いが分からなかった

JOI2010春Day1-stairs.cpp

#include <bits/stdc++.h>
using namespace std;

#define times(n, i) uptil(0, n, i)
#define upto(f, t, i) for(auto _##i = (t), i = decltype(_##i)(f); i <= _##i; i++)
#define uptil(f, t, i) for(auto _##i = (t), i = decltype(_##i)(f); i < _##i; i++)
#define downto(f, t, i) for(auto _##i = (t), i = decltype(_##i)(f); i >= _##i; i--)
#define downtil(f, t, i) for(auto _##i = (t), i = decltype(_##i)(f); i > _##i; i--)
#define unless(c) if(!(c))
#define until(c) while(!(c))
#define loop while(true)

const int Mod = 1234567;

int main(){
    int N, P;
    scanf("%d %d", &N, &P);
    vector<int> H(N);
    times(N, k) scanf("%d", &H[k]);
    vector<int> pyon(N + 1, 0);
    pyon[0] = 1;
    int old_k = 0, old_pyon = pyon[0], pyon_dist = 0;
    times(N, k){
        pyon_dist += H[k];
        until(pyon_dist <= P){
            old_pyon = (old_pyon - pyon[old_k] + Mod) % Mod;
            pyon_dist -= H[old_k];
            old_k++;
        }
        pyon[k + 1] = old_pyon;
        old_pyon = old_pyon * 2 % Mod;
        // old_pyon += pyon[k + 1] = old_pyon % Mod;
    }
    printf("%d\n", pyon[N] % Mod);
    return 0;
}