51Nod 1019树状数组离散化

开始RE,后面终于想通，数是10^9,然后离散化一下就行了；

#include<iostream>#include<cstdio>#include<cstring>#include<cmath>#include<vector>#include<algorithm>#include<map>using namespace std;const int maxn = 100000 + 10;#define INF 0x3f3f3f3f#define clr(x,y) memset(x,y,sizeof x )typedef long long ll;#define eps 10e-10const int Mod = 1000000007;typedef pair<ll, ll> P;ll tree[maxn];ll a[maxn];inline lowbit(ll x){    return x &(- x);}ll get(ll x){    ll ans = 0;    for(ll i = x; i > 0; i -= lowbit(i))        ans += tree[i];    return ans;}void update(ll x,ll val){    for(ll i = x; i < maxn; i += lowbit(i))        tree[i] += val;}int b[maxn];int main(){    ll n;    while( ~ scanf("%I64d",&n))    {        clr(tree,0);        for(ll i = 1; i <= n; i ++)            scanf("%I64d",&a[i]),b[i] = a[i];        sort(b+1,b+n+1);        int len = unique(b+1,b+n+1) - b;        for(int i = 1; i <= n; i ++)            a[i] = lower_bound(b+1,b+len + 1,a[i]) - b + 2;//        for(int i = 1; i <= n; i ++)//            cout << a[i] << " ";//        cout << endl;        ll ans = 0;        for(ll i = n; i >= 1; i --)        {            ans += get(a[i]);            update(a[i],1);        }        printf("%I64d\n",ans);    }    return 0;}