63 lines
1.3 KiB
C++
63 lines
1.3 KiB
C++
#include<iostream>
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#include<cstdio>
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#include<cstring>
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#include<algorithm>
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#include<cmath>
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#include<queue>
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#include<stack>
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#include<vector>
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#include<set>
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#include<map>
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#define L(x) (x<<1)
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#define R(x) (x<<1|1)
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#define MID(x,y) ((x+y)>>1)
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#define eps 1e-8
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#define fre(i,a,b) for(i = a; i <b; i++)
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#define free(i,b,a) for(i = b; i >= a;i--)
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#define mem(t, v) memset ((t) , v, sizeof(t))
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#define ssf(n) scanf("%s", n)
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#define sf(n) scanf("%d", &n)
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#define sff(a,b) scanf("%d %d", &a, &b)
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#define sfff(a,b,c) scanf("%d %d %d", &a, &b, &c)
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#define pf printf
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#define bug pf("Hi\n")
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using namespace std;
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typedef __int64 ll;
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#define INF 0x3f3f3f3f
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#define N 10005
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ll C(ll a,ll b)
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{
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ll x=1,y=1;
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ll i;
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b=min(b,a-b);
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if(b==0) return 1;
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fre(i,1,b+1)
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{
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x=x*a;
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y=y*i;
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a--;
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}
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return x/y;
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}
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ll fdd(ll x,ll y)
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{
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if(y==0) return x;
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return fdd(y,x%y);
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}
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int main()
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{
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ll i,j;
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ll n,m;
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while(~scanf("%I64d%I64d",&n,&m))
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{
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j=min(n,m);
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ll ans=0;
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fre(i,1,j+1)
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ans=ans+i*C(n,i)*C(m,i);
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ll y=C(n+m,n);
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ll x=fdd(ans,y);
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pf("%I64d/%I64d\n",ans/x,y/x);
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}
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return 0;
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}
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