7
COULD ANYONE EXPLAIN?
source link: https://codeforces.com/blog/entry/117124
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For the problem 1827A - Counting Orders, when in the question they mentioned that two reorderings are different, if the resultant array is different. When I check the submitted code with the below testcase, I got answer 4. But when I dry run for the testcase in the note, I found the resultant array are same. Hence the unique ways of reordering must be 2. Anyone plz explain and don't downvote for the question. Thanks in advance.
CODE
int n;
cin >> n;
vector<int> a(n), b(n);
for(int i = 0; i < n; i++) cin >> a[i];
for(int i = 0; i < n; i++) cin >> b[i];
sort(a.begin(), a.end());
sort(b.begin(), b.end());
ll ans = 1ll;
bool flag = false;
if(a[n - 1] <= b[n - 1]) flag = true;
else {
int i = 0, j = 0, cnt = 0;
while(i < n) {
int val = a[i];
while(j < n && val > b[j]) {
j++;
}
ll res = (j - i);
ans *= (res % mod);
ans %= mod;
i++;
}
}
if(flag) cout << 0 << endl;
else cout << ans << endl;Recommend
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