HDU 1394 Minimum Inversion Number (violence/Line tree)

title Link: http://acm.hdu.edu.cn/showproblem.php?pid=1394
violence (TIME:453MS)

#include <stdio.h> #define MAXN 5005int a[maxn];int Main () {    int n,i,j;    while (~SCANF ("%d", &n))    {        int ans=0x3f3f3f3f;        for (i=0; i<n; i++)            scanf ("%d", &a[i]);        int sum=0;        For (i=0, i<n; i++) for            (j=i+1; j<n; j + +)                if (A[i]>a[j])                    sum++;        if (ans>sum)            ans=sum;        for (i=0; i<n; i++)        {            sum=sum-a[i]+n-1-a[i];            if (ans>sum)                ans=sum;        }        printf ("%d\n", ans);    }    return 0;}

Segment Tree (TIMES:93MS)

#include <cstdio> #include <iostream> #include <sstream> #include <cstdlib> #include < cstring> #include <string> #include <climits> #include <cmath> #include <algorithm> #include <queue> #include <vector> #include <stack> #include <set> #include <map>using namespace STD; #define Lson L, M, RT << 1#define Rson m+1, R, RT << 1 | 1#define root 0,n-1,1const int mx=5000+5;int s[mx<<2];void push_up (int rt) {S[rt]=s[rt<<1]+s[rt<<1|1 ];}    void build (int l,int R,int RT) {s[rt]=0;    if (l==r) return;    int m= (L+R) >>1;    Build (Lson); Build (Rson);}        void update (int x,int l,int R,int rt) {if (l==r) {s[rt]=1;    return;    } int m= (L+R) >>1;    if (x<=m) update (X,lson);    else update (X,rson); PUSH_UP (RT);}    int query (int l,int r,int l,int r,int RT) {if (l<=l&&r<=r) return S[RT];    int m= (L+R) >>1,ret=0;     if (l<=m)   Ret+=query (L,r,lson);    if (r>m) ret+=query (L,r,rson); return ret;}    int main () {int N,X[MX];        while (~SCANF ("%d", &n)) {build (root);        int sum=0;            for (int i=0; i<n; i++) {scanf ("%d", &x[i]);            Sum+=query (X[i],n-1,root);        Update (X[I],ROOT);        } int cnt=sum;            for (int i=0; i<n; i++) {sum=sum-x[i]+n-1-x[i];        if (sum<cnt) cnt=sum;    } printf ("%d\n", CNT); } return 0;}

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HDU 1394 Minimum Inversion Number (violence/Line tree)