Unable to implement pseudocode

Question

I came across a pseudocode which I am unable to implement because, I am unable to understand it:

i, c := 0,0;
do i ≠ n →
    if v = b[i]           → c, i := c + 2, i + 1
       c = i               → c, i, v := c + 2, i + 1, b[i]
       c ≠ i ^ v ≠ b[i]    → i := i + 1
    fi
od

I think that tis pseudocode is about finding the value v which has occurred more than n / 2 times in b[].

Answer 1

The three conditions in the if are alternatives, they should be translated to an if-else if-else chain. The assignment-like statements c,i,v := c+2, i+1, b[i] are multiple assignments, as far as I know like the Python multiple assignments, so the i in b[i] refers to the old value of i. That yields

// n and v are initialised to something sensible, hopefully
i = 0;
c = 0;
while(i != n) {
    if (b[i] == v) {
        c = c + 2;
        i = i + 1;
    } else if (c == i) {
        c = c + 2;
        v = b[i];  // conjecture that the b[i] on the RHS refers to the old i
        i = i + 1;
    } else {
        i = i + 1;
    }
}

Since i is incremented in every branch, we can lift that out, and get

for(i = 0, c = 0; i != n; ++i) {
    if (b[i] == v) {
        c += 2;
    } else if (c == i) {
        c += 2;
        v = b[i];
    }
}