树状数组和线段树的解法比较,感觉不论在内存还是时间上都是树状数组占优
大题思路对 v从小到大进行排序,之后找之前的(也就是比v小的坐标)
v * sum(abs(xi - x)) 这样的话 abs无法处理,我们用另外一个树状数组记录在x ~ y区间牛的个数,之前那个记录在x ~ y区间内牛的坐标和
Accepted |
484 | 79 |
C++ |
1131 |
树状数组代码:
#include<cstdio> #include<algorithm> #include<cstring> using namespace std; typedef long long LL; const int maxn = 22222; int C1[maxn],C2[maxn]; int n = 20005,nn; struct Cow{ int v,x; friend bool operator < (Cow p,Cow q){ return p.v < q.v; } }cow[maxn]; int lowbit(int x){ return x & -x; } int sum(int C[],int x){ int ret = 0; while(x > 0){ ret += C[x]; x -= lowbit(x); } return ret; } void add(int C[],int x,int d){ while(x <= n){ C[x] += d; x += lowbit(x); } } int main(){ scanf("%d",&nn); memset(C1,0,sizeof(C1)); memset(C2,0,sizeof(C2)); for(int i = 0; i < nn; i++) scanf("%d%d",&cow[i].v,&cow[i].x); sort(cow,cow + nn); LL ans = 0; for(int i = 0; i < nn; i++){ int x = cow[i].x,v = cow[i].v; int m1 = sum(C1,x),n1 = sum(C2,x); int m2 = sum(C1,n) - m1,n2 = sum(C2,n) - n1; ans += (((LL)n1 * x - m1) + ((LL)m2 - n2 * x)) * v; add(C1,x,x); add(C2,x,1); } printf("%I64d\n",ans); return 0; }
I |
Accepted |
932 | 110 |
C++ |
1723 |
线段树代码:
#include<cstdio> #include<cstring> #include<algorithm> using namespace std; const int maxn = 20005; typedef long long LL; /*线段树解法*/ #define lson (pos<<1) #define rson (pos<<1|1) int v1[maxn << 2],v2[maxn << 2]; struct Node{ int x,v; friend bool operator < (Node p,Node q){ return p.v < q.v; } }node[maxn]; void build(){ memset(v1,0,sizeof(v1)); memset(v2,0,sizeof(v2)); } void pushup(int v[],int pos){ v[pos] = v[lson] + v[rson]; } void update(int v[],int L,int R,int aim,int pos,int value){ if(L == R){ v[pos] += value; return; } int mid = (L + R) >> 1; if(aim <= mid) update(v,L,mid,aim,lson,value); else update(v,mid + 1,R,aim,rson,value); pushup(v,pos); } int query(int v[],int L,int R,int l,int r,int pos){ if(l <= L && R <= r){ return v[pos]; } int mid = (L + R) >> 1; int ans = 0; if(l <= mid) ans += query(v,L,mid,l,r,lson); if(r > mid) ans += query(v,mid + 1,R,l,r,rson); return ans; } int main(){ build(); int n,max_size = 0; scanf("%d",&n); for(int i = 0; i < n; i++){ scanf("%d%d",&node[i].v,&node[i].x); max_size = max(max_size,node[i].x) + 1; } sort(node,node + n); LL ans = 0; for(int i = 0; i < n; i++){ int x = node[i].x,v = node[i].v; ans += ((LL)(x * query(v2,1,max_size,1,x,1)) - (LL)(query(v1,1,max_size,1,x,1))) * v; ans += ((LL)(query(v1,1,max_size,x,max_size,1)) - (LL)(query(v2,1,max_size,x,max_size,1) * x)) * v; //printf("%d %I64d\n",i,ans); update(v2,1,max_size,x,1,1); update(v1,1,max_size,x,1,x); } printf("%I64d\n",ans); return 0; }
时间: 2024-10-12 00:04:59