CodeforcesRound#261(Div.2)D樹狀數組應用_html/css

int n;int aa[1000000 + 55];int bb[1000000 + 55];int c[1000000 + 55];map	mp;ll lowbit(ll x) {	return x&(-x);}void add(int i,int val) {	while(i <= n) {	c[i] += val;	i += lowbit(i);	}}ll get_sum(int i) {	ll sum = 0;	while(i) {	sum += c[i];	i -= lowbit(i);	}	return sum;}void init() {	memset(c,0,sizeof(c));	memset(aa,0,sizeof(aa));	memset(bb,0,sizeof(bb));	mp.clear();}int main() {	while(scanf("%d",&n) == 1) {	init();	for(int i=1;i<=n;i++)scanf("%d",&aa[i]);	for(int i=1;i<=n;i++) {	mp[aa[i]]++;	bb[i] = mp[aa[i]];	add(bb[i],1);	}	mp.clear();	ll ans = 0ll;	for(int i=n;i>=1;i--) {	add(bb[i],-1);	mp[aa[i]]++;	int tmp = mp[aa[i]];	ans += i - get_sum(tmp) - 1;	}	cout< 




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