Kickstart 2021 D: Cutting Intervals, scanf vs cin

,
1

So I checking out the “Analysis” for the Cutting Intervals problem and wrote this

void solve(int testcase) {
ll n, c; scanf("%lld %lld", &n, &c);

map<ll, ll> m;
fo(_, 0, n) {
    ll tl, tr; scanf("%lld %lld", &tl, &tr);
    ++m[tl+1], --m[tr];
}

// iter(x, m) printf("{%lld: %lld}, ", x.first, x.second);
// printf("\n");

map<ll, ll> a;
ll j = 0;
auto mprev = m.begin(), mcurr = ++m.begin();

while (mcurr != m.end()) {
    ll kprev = mprev->first, kcurr = mcurr->first;
    // printf("%lld %lld\n", kprev, kcurr);

    j += mprev->second;
    a[j] += kcurr - kprev;

    ++mprev, ++mcurr;
}

// iter(x, a) printf("{%lld: %lld}, ", x.first, x.second);
// printf("\n");

ll res = n;
for (auto it = a.rbegin(); it != a.rend(); ++it) {
    res += it->first * min(it->second, c);
    c -= min(it->second, c);

    if (c == 0) break;
}

printf("Case #%d: %lld\n", testcase, res);

}

I believe the macros are self-explanatory. This gave “Sample Failed”. However, it worked on my machine. So I sent a manual “Run Test” and the output was Case #1: 1144119736199078559
instead of Case #1: 7. But then when I switched to cin over scanf it gave AC.

Any idea why?

2

@ssjgz, tagging you because I have seen you answering such questions before.
(Apologies if you don’t want to be tagged like this and I’ll keep this in mind next time)

3

Were you using Fast input output ?

4

Yes! I thought it just caused cin and and scanf to be out of sync, so I made sure to only use `scanf.