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Merge pull request fnplus#332 from orientor/CompleteModularExpo

Modular Exponentiation in C, Python and Java

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	`1`	`+// Iterative C program to compute modular power`
	`2`	`+#include <stdio.h>`
	`3`	`+`
	`4`	`+/* Iterative Function to calculate (x^y)%p in O(log y) */`
	`5`	`+int power(int x, unsigned int y, int p)`
	`6`	`+{`
	`7`	`+ int res = 1; // Initialize result`
	`8`	`+`
	`9`	`+ x = x % p; // Update x if it is more than or`
	`10`	`+ // equal to p`
	`11`	`+`
	`12`	`+ while (y > 0)`
	`13`	`+ {`
	`14`	`+ // If y is odd, multiply x with result`
	`15`	`+ if (y & 1)`
	`16`	`+ res = (res*x) % p;`
	`17`	`+`
	`18`	`+ // y must be even now`
	`19`	`+ y = y>>1; // y = y/2`
	`20`	`+ x = (x*x) % p;`
	`21`	`+ }`
	`22`	`+ return res;`
	`23`	`+}`
	`24`	`+`
	`25`	`+// Driver program to test above functions`
	`26`	`+int main()`
	`27`	`+{`
	`28`	`+ int x = 2;`
	`29`	`+ int y = 5;`
	`30`	`+ int p = 13;`
	`31`	`+ printf("Power is %u", power(x, y, p));`
	`32`	`+ return 0;`
	`33`	`+}`

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	`1`	`+// Iterative Java program to`
	`2`	`+// compute modular power`
	`3`	`+import java.io.*;`
	`4`	`+`
	`5`	`+class GFG {`
	`6`	`+`
	`7`	`+ /* Iterative Function to calculate`
	`8`	`+ (x^y)%p in O(log y) */`
	`9`	`+ static int power(int x, int y, int p)`
	`10`	`+ {`
	`11`	`+ // Initialize result`
	`12`	`+ int res = 1;`
	`13`	`+`
	`14`	`+ // Update x if it is more`
	`15`	`+ // than or equal to p`
	`16`	`+ x = x % p;`
	`17`	`+`
	`18`	`+ while (y > 0)`
	`19`	`+ {`
	`20`	`+ // If y is odd, multiply x`
	`21`	`+ // with result`
	`22`	`+ if((y & 1)==1)`
	`23`	`+ res = (res * x) % p;`
	`24`	`+`
	`25`	`+ // y must be even now`
	`26`	`+ // y = y / 2`
	`27`	`+ y = y >> 1;`
	`28`	`+ x = (x * x) % p;`
	`29`	`+ }`
	`30`	`+ return res;`
	`31`	`+ }`
	`32`	`+`
	`33`	`+ // Driver Program to test above functions`
	`34`	`+ public static void main(String args[])`
	`35`	`+ {`
	`36`	`+ int x = 2;`
	`37`	`+ int y = 5;`
	`38`	`+ int p = 13;`
	`39`	`+ System.out.println("Power is " + power(x, y, p));`
	`40`	`+ }`
	`41`	`+}`

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	`1`	`+# Iterative Python3 program`
	`2`	`+# to compute modular power`
	`3`	`+`
	`4`	`+# Iterative Function to calculate`
	`5`	`+# (x^y)%p in O(log y)`
	`6`	`+def power(x, y, p) :`
	`7`	`+ res = 1 # Initialize result`
	`8`	`+`
	`9`	`+ # Update x if it is more`
	`10`	`+ # than or equal to p`
	`11`	`+ x = x % p`
	`12`	`+`
	`13`	`+ while (y > 0) :`
	`14`	`+`
	`15`	`+ # If y is odd, multiply`
	`16`	`+ # x with result`
	`17`	`+ if ((y & 1) == 1) :`
	`18`	`+ res = (res * x) % p`
	`19`	`+`
	`20`	`+ # y must be even now`
	`21`	`+ y = y >> 1 # y = y/2`
	`22`	`+ x = (x * x) % p`
	`23`	`+`
	`24`	`+ return res`
	`25`	`+`
	`26`	`+`
	`27`	`+# Driver Code`
	`28`	`+`
	`29`	`+x = 2; y = 5; p = 13`
	`30`	`+print("Power is ", power(x, y, p))`

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