Programming/decode.cpp at master · arshdeep/Programming · GitHub

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#include<iostream>
#include<cstring>
usingnamespacestd;

// A Dynamic Programming based function to count decodings
intcountDecodingDP(char *digits, int n)
{
int count[101]; // A table to store results of subproble
	count[0] = 1;
if (digits[0] >='1' && digits[0] <= '9')
 count[1] = 1;
elsereturn0;

for (int i = 2; i <= n; i++)
 {
if (digits[i - 1] >='1' && digits[i - 1] <= '9')
 {
if ((digits[i-2] == '1' && digits[i-1] >='0' && digits[i-1] <= '9')
 || digits[i-2] == '2' && digits[i-1] >='0' && digits[i-1] <= '6')
 count[i] = count[i -1] + count[i-2];
else
 count[i] = count[i-1];
 }
else
 {
if ((digits[i-2] == '1' && digits[i-1] >='0' && digits[i-1] <= '9')
 || digits[i-2] == '2' && digits[i-1] >='0' && digits[i-1] <= '6')
 count[i] = count[i-2];
else
return0;
 }


 }
return count[n];
}

// Driver program to test above function
intmain()
{
char digits[] = "109";
int n = strlen(digits);
 cout << "Count is " << countDecodingDP(digits, n);
return0;
}