hdu 2838

来源：互联网发布：死逝君馆芽吹憎恶知乎编辑：程序博客网时间：2024/05/16 05:19

#include <iostream>#include <cstdio>#include <cstdlib>#include <algorithm>#include <vector>#include <map>#include <set>#include <string>#include <cstring>#include <list>#include <queue>#include <stack>#include <cmath>using namespace std;#define PF(x) (scanf("%d",&x))#define PT(x,y) (scanf("%d%d",&x,&y))#define PR(x) (printf("%d\n",(x)))#define PRT(x,y)(printf("%d %d\n",x,y))#define M 100005typedef __int64 LL;LL arr[M];LL n,m;LL ar[M];int maxx(int x,int y){return x>y?x:y;}int minx(int x,int y){return x>y?y:x;}LL low(LL x){return x&(-x);}void add(LL *ac,LL x,LL c){for(x;x<M;x+=low(x))ac[x]+=c;}LL sums(LL *ac,LL x){LL sumt = 0;for(;x;x-=low(x))sumt += ac[x];return sumt;}void init(){while(scanf("%I64d",&n)!=EOF){memset(arr,0,sizeof(arr));memset(ar,0,sizeof(ar));    LL ans = 0;for(int i=0;i<n;i++){LL x;scanf("%I64d",&x);ans += sums(arr,n)-sums(arr,x)+(sums(ar,n)-sums(ar,x))*x;add(arr,x,x);add(ar,x,1);}printf("%I64d\n",ans);}return ;}int main(){init();return 0;}