"HDU 4311" meeting point-1 (prefix and find Manhattan distance and)

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Serious solution:

Given the coordinates of n points, find a point, and the smallest distance to other points of Manhattan.
n can be 100000.
An O (NLOGN) algorithm is probably needed.
The Euclidean distance can be calculated by dividing X and y to calculate the prefix and to determine the distance from one point to another within the O (1) time.

#include <cstdio> #include <algorithm>using namespace std; #define LL Long long#define N 100005int t,n;ll ans,    sum[n],sx[n],sy[n];struct p{int i; ll x, y;} A[n];int cmpx (P a,p b) {return a.x<b.x;} int Cmpy (P a,p b) {return a.y<b.y;}    int main () {scanf ("%d", &t);        while (t--) {sx[0]=sy[0]=0;        scanf ("%d", &n);            for (int i=1; i<=n; i++) {scanf ("%lld%lld", &a[i].x,&a[i].y);        A[i].i=i;        } sort (A+1,A+N+1,CMPX);        for (int i=1; i<=n; i++) sx[i]=sx[i-1]+a[i].x;        for (int i=1;i<=n;i++) sum[a[i].i]=a[i].x* (i-1)-sx[i-1]+sx[n]-sx[i]-a[i].x* (n-i);        Sort (a+1,a+n+1,cmpy);        for (int i=1; i<=n; i++) sy[i]=sy[i-1]+a[i].y;            for (int i=1; i<=n; i++) {sum[a[i].i]+=a[i].y* (i-1)-sy[i-1]+sy[n]-sy[i]-a[i].y* (n-i);        Ans= (i==1) sum[a[1].i]:min (ans,sum[a[i].i]);    } printf ("%lld\n", ans); }}

Narrowing the scope method:

Another way, I thought so, but later did not dare to pay, I think it will WA.
Because it is not very reliable in itself.
After sorting by X, take the near point of the middle X to calculate (after I have repeatedly submitted, found that this range can not be less than ±220, this is the difficult point, why is about 250, the game on the basis of intuition value).

#include <cstdio> #include <algorithm>using namespace std; #define LL Long longstruct p{ll x, y;} A[100005];ll ABS (ll a) {    if (a<0) a=-a;    return A;} ll DIS (p a, p b) {    return ABS (a.x-b.x) +abs (A.Y-B.Y);} int CMP (P a,p b) {    return a.x<b.x;} int main () {    int t,n,s,e;    scanf ("%d", &t);    while (t--) {        scanf ("%d", &n);        for (int i=1;i<=n;i++)            scanf ("%lld%lld", &a[i].x,&a[i].y);        Sort (a+1,a+1+n,cmp);        s=n/2-223;        e=n/2+223;        if (s<1) S=1;        if (e>n) e=n;        ll ans=1ll<<60;        for (int z=s;z<=e;z++) {            ll s=0;            for (int i=1;i<=n;i++)                S+=dis (A[z],a[i]);            Ans=min (S,ans);        }        printf ("%lld\n", ans);}    }

　　

HDU 4311 Meeting point-1 (prefix and find Manhattan distance and)