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55 lines
1.1 KiB
C++
55 lines
1.1 KiB
C++
/*
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* C++ Program to Implement Extended Eucledian Algorithm
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*/
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#include <iostream>
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#include <utility>
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using namespace std;
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/* return the gcd of a and b followed by the pair x and y of
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equation ax + by = gcd(a,b)
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*/
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pair<int, pair<int, int> > extendedEuclid(int a, int b)
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{
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int x = 1, y = 0;
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int xLast = 0, yLast = 1;
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int q, r, m, n;
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while (a != 0)
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{
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q = b / a;
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r = b % a;
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m = xLast - q * x;
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n = yLast - q * y;
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xLast = x;
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yLast = y;
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x = m;
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y = n;
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b = a;
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a = r;
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}
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return make_pair(b, make_pair(xLast, yLast));
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}
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int modInverse(int a, int m)
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{
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return (extendedEuclid(a, m).second.first + m) % m;
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}
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//Main
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int main()
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{
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int a, m;
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cout<<"Enter number to find modular multiplicative inverse: ";
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cin>>a;
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cout<<"Enter Modular Value: ";
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cin>>m;
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cout<<modInverse(a, m)<<endl;
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}
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/*
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Enter number to find modular multiplicative inverse: 133
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Enter Modular Value: 135
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67
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------------------
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(program exited with code: 1)
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Press return to continue
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