The Naive String Matching Algorithm
The na´ve approach tests all the possible placement of Pattern P [1.......m] relative to text T [1......n]. We try shift s = 0, 1.......n-m, successively and for each shift s. Compare T [s+1.......s+m] to P [1......m].
The na´ve algorithm finds all valid shifts using a loop that checks the condition P [1.......m] = T [s+1.......s+m] for each of the n - m +1 possible value of s.
NAIVE-STRING-MATCHER (T, P) 1. n ← length [T] 2. m ← length [P] 3. for s ← 0 to n -m 4. do if P [1.....m] = T [s + 1....s + m] 5. then print "Pattern occurs with shift" s
Analysis: This for loop from 3 to 5 executes for n-m + 1(we need at least m characters at the end) times and in iteration we are doing m comparisons. So the total complexity is O (n-m+1).