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  • hdu 1695 GCD 莫比乌斯

    GCD

    Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
    Total Submission(s): 9765    Accepted Submission(s): 3652


    Problem Description
    Given 5 integers: a, b, c, d, k, you're to find x in a...b, y in c...d that GCD(x, y) = k. GCD(x, y) means the greatest common divisor of x and y. Since the number of choices may be very large, you're only required to output the total number of different number pairs.
    Please notice that, (x=5, y=7) and (x=7, y=5) are considered to be the same.

    Yoiu can assume that a = c = 1 in all test cases.
     
    Input
    The input consists of several test cases. The first line of the input is the number of the cases. There are no more than 3,000 cases.
    Each case contains five integers: a, b, c, d, k, 0 < a <= b <= 100,000, 0 < c <= d <= 100,000, 0 <= k <= 100,000, as described above.
     
    Output
    For each test case, print the number of choices. Use the format in the example.
     
    Sample Input
    2 1 3 1 5 1 1 11014 1 14409 9
     
    Sample Output
    Case 1: 9 Case 2: 736427
    Hint
    For the first sample input, all the 9 pairs of numbers are (1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (2, 3), (2, 5), (3, 4), (3, 5).
     
    Source
    #include<bits/stdc++.h>
    using namespace std;
    #define ll long long
    #define esp 0.00000000001
    #define pi 4*atan(1)
    const int N=1e5+10,M=1e7+10,inf=1e9+10,mod=1e9+7;
    int mu[N], p[N], np[N], cnt, sum[N];
    void init() {
        mu[1]=1;
        for(int i=2; i<N; ++i) {
            if(!np[i]) p[++cnt]=i, mu[i]=-1;
            for(int j=1; j<=cnt && i*p[j]<N; ++j) {
                int t=i*p[j];
                np[t]=1;
                if(i%p[j]==0) { mu[t]=0; break; }
                mu[t]=-mu[i];
            }
        }
    }
    int main()
    {
        int T,cas=1;
        init();
        scanf("%d",&T);
        while(T--)
        {
            int a,b,c,d,k;
            scanf("%d%d%d%d%d",&a,&b,&c,&d,&k);
            if(k==0)
            {
                printf("Case %d: 0
    ",cas++);
                continue;
            }
            b/=k,d/=k;
            if(b>=d)swap(b,d);
            ll ans=0;
            for(int i=1;i<=b;i++)
            {
                ans+=(ll)mu[i]*(b/i)*(d/i);
            }
            ll ans2=0;
            for(int i=1;i<=b;i++)
            {
                ans2+=(ll)mu[i]*(b/i)*(b/i);
            }
            printf("Case %d: %lld
    ",cas++,ans-ans2/2);
        }
        return 0;
    }
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  • 原文地址:https://www.cnblogs.com/jhz033/p/5783594.html
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