Submission Week Eight

week08/basic_calculator_ii.cpp

@@ -0,0 +1,32 @@
+// Time complexity: O(N), N = Number of characters in the string.
+// Space complexity: O(total count of possible numbers in the string)
+
+int calculate(string s){
+    long long currNum = 0;
+    long result = 0;
+    stack<int> stk;
+    char sign = '+';
+    int s_length = s.size();
+    for(int i = 0; i < s_length; i++){
+        if(s[i] >= '0' && s[i] <= '9'){
+            currNum = 10 * currNum + s[i] - '0';
+        }
+        if(!(s[i] >= '0' && s[i] <= '9') && (s[i] != ' ') || i == s_length - 1){
+            if(sign == '+') stk.push(currNum);
+            else if(sign == '-') stk.push(-1 * currNum);
+            else{
+                if(sign == '*') currNum = stk.top() * currNum;
+                else currNum = stk.top() / currNum;
+                stk.pop();
+                stk.push(currNum);
+            }
+            currNum = 0;
+            sign = s[i];
+        }
+    }
+    while(!stk.empty()){
+        result += stk.top();
+        stk.pop();
+    }
+    return result;
+}

week08/count_primes.cpp

@@ -0,0 +1,24 @@
+// Time complexity: O(square_root(N) * log(log(N)) , N = Given integer number.
+// Space complexity: O(N)
+
+int sieve(int n){
+    vector<bool> comp(n + 5, false);
+    comp[1] = true;
+    for(int i = 2; i * i <= n; i++){
+        if(comp[i] == false){
+            for(int j = i * i; j <= n; j += i){
+                comp[j] = true;
+            }
+        }
+    }
+    int count = 1;
+    for(int i = 3; i < n; i += 2){
+        if(comp[i] == false) count++;
+    }
+    return count;
+}
+
+int countPrimes(int n){
+    if(n == 0 || n == 1 || n == 2) return 0;
+    return sieve(n);
+}

week08/factorial_trailing_zeroes.cpp

@@ -0,0 +1,11 @@
+//Time complexity: O(Count of 5 in the n's factorial's divisors).
+//Space complexity: O(1)
+int trailingZeroes(int n){
+    int count_5 = 0;
+    int div = 5;
+    while(n >= div){
+        count_5 += n / div;
+        div *= 5;
+    }
+    return count_5;
+}

week08/guess_the_word.cpp

@@ -0,0 +1,27 @@
+// Time complexity: O(N), N = Number of strings.
+// Space complexity: O(N)
+
+int calculateScore(string &ref, string &candidate){
+    int res = 0;
+    int ref_length = ref.size();
+    for(int i = 0; i < ref_length; i++){
+        res += ref[i] == candidate[i];
+    }
+    return res;
+}
+
+void findSecretWord(vector<string> &wordlist, Master &master){
+    while(wordlist.size() > 1){
+        int rnd_index = rand() % wordlist.size();
+        string query_string = wordlist[rnd_index];
+        int score = master.guess(query_string);
+        vector<string> new_word_list;
+        for(auto &word: wordlist){
+            if(calculateScore(word, query_string) == score){
+                new_word_list.push_back();
+            }
+        }
+        wordlist = new_word_list;
+    }
+    master.quess(wordlist[0]);
+}

week08/powx_n.cpp

@@ -0,0 +1,20 @@
+// Time complexity: O(log N), N is the power of the base.
+// Space complexity: O(1)
+
+double modularExpo(double x, long long n){
+    if(n == 0) return 1.0;
+    if(n % 2 == 0){
+        double res = modularExpo(x, n / 2);
+        return res * res;
+    }
+    return x * modularExpo(x, n - 1);
+}
+
+double myPow(double x, int n){
+    if(n == 0) return 1.0;
+    bool inverse_flag = n < 0;
+    long long N = n < 0? (-1) * 1LL * n : n;
+    double result = modularExpo(x, N);
+    result = inverse_flag ? 1.0 / result : result;
+    return result;
+}

week08/sqrtx.cpp

@@ -0,0 +1,12 @@
+// Time complexity: O(log N) , N = given Number;
+// Space complexity: O(1)
+
+int mySqrt(int x){
+    long long left = 0, right = x;
+    while(left < right){
+        long long mid = left + (right - left + 1) / 2;
+        if(mid * mid > x) right = mid - 1;
+        else left = mid;
+    }
+    return right;
+}