seventh又来出题了 子区间的和大于等于0 逆序对+前缀和

http://120.78.128.11/Problem.jsp?pid=3087



给你一个序列{a1,a2,a2...an},求有多少对(l,r),满足

image.png

就是求有多少个子区间的和大于等于0 


维护一个前缀和,然后有多少子区间和≥0就是,前缀和这些有多少

顺序对,顺序对=总-逆序对。


///                 .-~~~~~~~~~-._       _.-~~~~~~~~~-.
///             __.'              ~.   .~              `.__
///           .'//                  \./                  \\`.
///        .'//                     |                     \\`.
///       .'// .-~"""""""~~~~-._     |     _,-~~~~"""""""~-. \\`.
///     .'//.-"                 `-.  |  .-'                 "-.\\`.
///   .'//______.============-..   \ | /   ..-============.______\\`.
/// .'______________________________\|/______________________________`.
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;

#define pi acos(-1)
#define s_1(x) scanf("%d",&x)
#define s_2(x,y) scanf("%d%d",&x,&y)
#define s_3(x,y,z) scanf("%d%d%d",&x,&y,&z)
#define s_4(x,y,z,X) scanf("%d%d%d%d",&x,&y,&z,&X)
#define S_1(x) scan_d(x)
#define S_2(x,y) scan_d(x),scan_d(y)
#define S_3(x,y,z) scan_d(x),scan_d(y),scan_d(z)
#define PI acos(-1)
#define endl '\n'
#define srand() srand(time(0));
#define me(x,y) memset(x,y,sizeof(x));
#define foreach(it,a) for(__typeof((a).begin()) it=(a).begin();it!=(a).end();it++)
#define close() ios::sync_with_stdio(0); cin.tie(0);
#define FOR(x,n,i) for(int i=x;i<=n;i++)
#define FOr(x,n,i) for(int i=x;i=x;i--)
#define fOr(n,x,i) for(int i=n;i>x;i--)
#define W while
#define sgn(x) ((x) < 0 ? -1 : (x) > 0)
#define bug printf("***********\n");
#define db double
#define ll long long
#define mp make_pair
#define pb push_back
typedef long long LL;
typedef pair  ii;
const int INF=0x3f3f3f3f;
const LL LINF=0x3f3f3f3f3f3f3f3fLL;
const int dx[]={-1,0,1,0,1,-1,-1,1};
const int dy[]={0,1,0,-1,-1,1,-1,1};
const int maxn=1e5+10;
const int maxx=1e3+10;
const double EPS=1e-8;
const double eps=1e-8;
const int mod=1e9+7;
templateinline T min(T a,T b,T c) { return min(min(a,b),c);}
templateinline T max(T a,T b,T c) { return max(max(a,b),c);}
templateinline T min(T a,T b,T c,T d) { return min(min(a,b),min(c,d));}
templateinline T max(T a,T b,T c,T d) { return max(max(a,b),max(c,d));}
template 
inline bool scan_d(T &ret){char c;int sgn;if (c = getchar(), c == EOF){return 0;}
while (c != '-' && (c < '0' || c > '9')){c = getchar();}sgn = (c == '-') ? -1 : 1;ret = (c == '-') ? 0 : (c - '0');
while (c = getchar(), c >= '0' && c <= '9'){ret = ret * 10 + (c - '0');}ret *= sgn;return 1;}

inline bool scan_lf(double &num){char in;double Dec=0.1;bool IsN=false,IsD=false;in=getchar();if(in==EOF) return false;
while(in!='-'&&in!='.'&&(in<'0'||in>'9'))in=getchar();if(in=='-'){IsN=true;num=0;}else if(in=='.'){IsD=true;num=0;}
else num=in-'0';if(!IsD){while(in=getchar(),in>='0'&&in<='9'){num*=10;num+=in-'0';}}
if(in!='.'){if(IsN) num=-num;return true;}else{while(in=getchar(),in>='0'&&in<='9'){num+=Dec*(in-'0');Dec*=0.1;}}
if(IsN) num=-num;return true;}

void Out(LL a){if(a < 0) { putchar('-'); a = -a; }if(a >= 10) Out(a / 10);putchar(a % 10 + '0');}
void print(LL a){ Out(a),puts("");}
//freopen( "in.txt" , "r" , stdin );
//freopen( "data.txt" , "w" , stdout );
//cerr << "run time is " << clock() << endl;
int aa[maxn];
int n;
LL sum[maxn];
LL c[maxn],a[maxn];
LL ans=0;
void x(int l,int r)   
{   
    int mid=(l+r)/2,i,j,tmp;   
    if(r>l)   
    {   
        x(l,mid);   
        x(mid+1,r);   
        tmp=l;   
        for(i=l,j=mid+1;i<=mid&&j<=r;)   
        {   
            if(a[i]>a[j])   
            {   
                c[tmp++]=a[j++];   
                ans+=mid-i+1;   
            }   
            else c[tmp++]=a[i++];   
        }   
        if(i<=mid) for(;i<=mid;) c[tmp++]=a[i++];   
        if(j<=r) for(;j<=r;) c[tmp++]=a[j++];   
        for(i=l;i<=r;i++) a[i]=c[i];   
    }   
}   


void solve()
{
	s_1(n);
	FOR(1,n,i) s_1(aa[i]);
	sum[0]=0;
	ans=0;
	me(a,0);
	me(c,0);
	FOR(1,n,i) 
	{
		sum[i]=sum[i-1]+aa[i];
		a[i]=sum[i];
	}
	x(1,n); 
    ans=(LL)n*(n-1)/2-ans;
    FOR(1,n,i)
		if(sum[i]>=0) ans++;
    printf("%lld\n",ans);
}
int main()
{
   // freopen( "in.txt" , "r" , stdin );
    //freopen( "data.txt" , "w" , stdout );
    int t=1;
    //init();
    s_1(t);
    for(int cas=1;cas<=t;cas++)
    {
        //printf("Case #%d: ",cas);
        solve();
    }
}


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