HDU 1394 Minimum Inversion Number 树状数组&&线段树
2014-06-30 19:26
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题目给了你一串序列,然后每次 把最后一个数提到最前面来,直到原来的第一个数到了最后一个,每次操作都会产生一个新的序列,这个序列具有一个逆序数的值,问最小的你逆序数的值为多少
逆序数么 最好想到的是树状数组,敲了一把很快,注意把握把最后一个数提上来对逆序数的影响即可,
#include<iostream>
#include<cstdio>
#include<list>
#include<algorithm>
#include<cstring>
#include<string>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#include<cmath>
#include<memory.h>
#include<set>
#include<cctype>
#define ll long long
#define LL __int64
#define eps 1e-8
#define inf 0xfffffff
//const LL INF = 1LL<<61;
using namespace std;
//vector<pair<int,int> > G;
//typedef pair<int,int > P;
//vector<pair<int,int> > ::iterator iter;
//
//map<ll,int >mp;
//map<ll,int >::iterator p;
int n;
int c[10000 + 5];
int num[10000 + 5];
void init() {
memset(c,0,sizeof(c));
memset(num,0,sizeof(num));
}
int lowbit(int x) {
return x&(-x);
}
void add(int i,int val) {
while(i <= n) {
c[i] += val;
i += lowbit(i);
}
}
int get_sum(int i) {
int sum = 0;
while(i > 0) {
sum += c[i];
i -= lowbit(i);
}
return sum;
}
int main() {
while(scanf("%d",&n) == 1) {
init();
int ans = 0;
for(int i=1;i<=n;i++) {
scanf("%d",&num[i]);
num[i]++;
add(num[i],1);
ans += (i - get_sum(num[i]));
}
int minn = ans;
for(int i=n;i>1;i--) {
ans = ans + num[i] + num[i] - n - 1;
minn = min(ans,minn);
}
printf("%d\n",minn);
}
return 0;
}
线段树:
#include<iostream>
#include<cstdio>
#include<list>
#include<algorithm>
#include<cstring>
#include<string>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#include<cmath>
#include<memory.h>
#include<set>
#include<cctype>
#define ll long long
#define LL __int64
#define eps 1e-8
#define inf 0xfffffff
//const LL INF = 1LL<<61;
using namespace std;
//vector<pair<int,int> > G;
//typedef pair<int,int > P;
//vector<pair<int,int> > ::iterator iter;
//
//map<ll,int >mp;
//map<ll,int >::iterator p;
const int N = 10000 + 5;
int num
;
typedef struct Node {
int a;
int l,r;
};
Node tree[N * 4];
void init() {
memset(tree,0,sizeof(tree));
memset(num,0,sizeof(num));
}
void cal(int id) {
tree[id].a = min(tree[id<<1].a,tree[id<<1|1].a);
}
void build(int l,int r,int id) {
tree[id].l = l;
tree[id].r = r;
tree[id].a = 0;
if(l == r) return ;
int mid = (l + r)/2;
build(l,mid,id<<1);
build(mid+1,r,id<<1|1);
}
void updata(int w,int id) {
if(tree[id]. l == w && tree[id].r == w) {
tree[id].a = 1;return;
}
int mid = (tree[id].l + tree[id].r)/2;
if(w <= mid) updata(w,id<<1);
else updata(w,id<<1|1);
tree[id].a = tree[id<<1].a + tree[id<<1|1].a;
}
int query(int l,int r,int id) {
if(l <= tree[id].l && r >= tree[id].r)return tree[id].a;
int mid = (tree[id].l + tree[id].r)/2;
int ans1 = 0,ans2 = 0;
if(l <= mid) ans1 = query(l,r,id<<1);
if(r > mid) ans2 = query(l,r,id<<1|1);
return ans1 + ans2;
}
int main() {
int n;
while(scanf("%d",&n) == 1) {
init();
build(1,n,1);
int ans = 0;
for(int i=0;i<n;i++) {
scanf("%d",&num[i]);
ans += query(num[i] + 1,n-1,1);
updata(num[i],1);
}
int minn = ans;
for(int i=0;i<n;i++) {
ans = ans + n - 2 * num[i] - 1;
minn = min(ans,minn);
}
printf("%d\n",minn);
}
return 0;
}
逆序数么 最好想到的是树状数组,敲了一把很快,注意把握把最后一个数提上来对逆序数的影响即可,
#include<iostream>
#include<cstdio>
#include<list>
#include<algorithm>
#include<cstring>
#include<string>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#include<cmath>
#include<memory.h>
#include<set>
#include<cctype>
#define ll long long
#define LL __int64
#define eps 1e-8
#define inf 0xfffffff
//const LL INF = 1LL<<61;
using namespace std;
//vector<pair<int,int> > G;
//typedef pair<int,int > P;
//vector<pair<int,int> > ::iterator iter;
//
//map<ll,int >mp;
//map<ll,int >::iterator p;
int n;
int c[10000 + 5];
int num[10000 + 5];
void init() {
memset(c,0,sizeof(c));
memset(num,0,sizeof(num));
}
int lowbit(int x) {
return x&(-x);
}
void add(int i,int val) {
while(i <= n) {
c[i] += val;
i += lowbit(i);
}
}
int get_sum(int i) {
int sum = 0;
while(i > 0) {
sum += c[i];
i -= lowbit(i);
}
return sum;
}
int main() {
while(scanf("%d",&n) == 1) {
init();
int ans = 0;
for(int i=1;i<=n;i++) {
scanf("%d",&num[i]);
num[i]++;
add(num[i],1);
ans += (i - get_sum(num[i]));
}
int minn = ans;
for(int i=n;i>1;i--) {
ans = ans + num[i] + num[i] - n - 1;
minn = min(ans,minn);
}
printf("%d\n",minn);
}
return 0;
}
线段树:
#include<iostream>
#include<cstdio>
#include<list>
#include<algorithm>
#include<cstring>
#include<string>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#include<cmath>
#include<memory.h>
#include<set>
#include<cctype>
#define ll long long
#define LL __int64
#define eps 1e-8
#define inf 0xfffffff
//const LL INF = 1LL<<61;
using namespace std;
//vector<pair<int,int> > G;
//typedef pair<int,int > P;
//vector<pair<int,int> > ::iterator iter;
//
//map<ll,int >mp;
//map<ll,int >::iterator p;
const int N = 10000 + 5;
int num
;
typedef struct Node {
int a;
int l,r;
};
Node tree[N * 4];
void init() {
memset(tree,0,sizeof(tree));
memset(num,0,sizeof(num));
}
void cal(int id) {
tree[id].a = min(tree[id<<1].a,tree[id<<1|1].a);
}
void build(int l,int r,int id) {
tree[id].l = l;
tree[id].r = r;
tree[id].a = 0;
if(l == r) return ;
int mid = (l + r)/2;
build(l,mid,id<<1);
build(mid+1,r,id<<1|1);
}
void updata(int w,int id) {
if(tree[id]. l == w && tree[id].r == w) {
tree[id].a = 1;return;
}
int mid = (tree[id].l + tree[id].r)/2;
if(w <= mid) updata(w,id<<1);
else updata(w,id<<1|1);
tree[id].a = tree[id<<1].a + tree[id<<1|1].a;
}
int query(int l,int r,int id) {
if(l <= tree[id].l && r >= tree[id].r)return tree[id].a;
int mid = (tree[id].l + tree[id].r)/2;
int ans1 = 0,ans2 = 0;
if(l <= mid) ans1 = query(l,r,id<<1);
if(r > mid) ans2 = query(l,r,id<<1|1);
return ans1 + ans2;
}
int main() {
int n;
while(scanf("%d",&n) == 1) {
init();
build(1,n,1);
int ans = 0;
for(int i=0;i<n;i++) {
scanf("%d",&num[i]);
ans += query(num[i] + 1,n-1,1);
updata(num[i],1);
}
int minn = ans;
for(int i=0;i<n;i++) {
ans = ans + n - 2 * num[i] - 1;
minn = min(ans,minn);
}
printf("%d\n",minn);
}
return 0;
}
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