.

problem-of-the-day/day13/AB Flipping.cpp

@@ -0,0 +1,37 @@
+#include<iostream>
+#include <stdlib.h>
+#include <vector>
+using namespace std;
+#define int long long
+#define rep(i, a, b) for (int i = a; i < b; i++)
+
+
+void solve() {
+    int n;string s;cin>>n>>s;
+    int ans = 0;
+    vector<bool>a(n+1,false),b(n+1,false);
+    b[n-1] = (s[n-1]=='B');
+    a[0] = (s[0]=='A');
+    for(int i = n-2;i>=0;i--){
+        b[i] = (s[i]=='B') || (b[i+1]);
+    }
+    rep(i,1,n){
+        a[i] = (s[i] == 'A') || (a[i-1]);
+    }
+    rep(i,0,n-1){
+        ans += a[i] && b[i+1];
+    }
+    cout<<ans<<'\n';
+}
+
+
+int32_t main() {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int t;
+  cin >> t;
+  while (t--) {
+    solve();
+  }
+  return 0;
+}

problem-of-the-day/day13/Digit Queries.cpp

@@ -0,0 +1,42 @@
+#include <algorithm>
+#include <bitset>
+#include <deque>
+#include <iostream>
+using namespace std;
+#define int long long
+// ------------------------------------------***--------------------------------------------------
+
+int pow(int i){
+    if(i==0)return 1;
+    return 10*pow(i-1);
+}
+
+vector<int>a;
+int32_t main() {
+    int curr = 1;
+    int digit = 1;
+    while(digit<=18){
+        a.push_back(curr);
+        curr+=9*digit*pow(digit-1);
+        digit++;
+    }
+    int q,qq;cin>>q;
+    while(q--){
+        cin>>qq;
+        int i = 0;
+        for(i = 0;i<18;i++){
+            if(a[i]>qq)break;
+        }
+        digit = i;
+        int base = pow(digit-1);
+        int offset = qq - a[digit-1];
+        base+=(offset)/digit;
+        offset%=digit;
+        // cout<<base<<' '<<digit<<' '<<offset<<'\n';
+        string num = to_string(base);
+        cout<<num[offset]<<'\n';
+        // if(offset==0)cout<<num[len(num)-1]<<'\n';
+        // else cout<<num[offset-1]<<'\n';
+    }
+  return 0;
+}

problem-of-the-day/day13/Even Number Addicts.cpp

@@ -0,0 +1,47 @@
+#include <bits/stdc++.h>
+#define endl '\n'
+
+typedef long long int ll;
+using namespace std;
+
+bool solve(int odd, int even, bool alice_winning, bool alice, vector<vector<vector<int>>>& memo) {
+    if(odd == 0 && even == 0) {
+        return alice_winning;
+    }
+    if(alice && memo[odd][even][alice_winning] != -1)
+        return memo[odd][even][alice_winning];
+    if(alice) {
+        bool option1 = false, option2 = false;
+        if(odd > 0)  option1 = solve(odd - 1, even, !alice_winning, false, memo);
+        if(even > 0) option2 = solve(odd, even - 1, alice_winning, false, memo);
+        return memo[odd][even][alice_winning] = max(option1, option2);
+    } else {
+        bool option1 = true, option2 = true;
+        if(odd > 0)  option1 = solve(odd - 1, even, alice_winning, true, memo);
+        if(even > 0) option2 = solve(odd, even - 1, alice_winning, true, memo);
+        return min(option1, option2);
+    }
+}
+
+int main() {
+    ios::sync_with_stdio(false);
+    cin.tie(NULL);
+
+    int t;
+    cin >> t;
+    while(t--) {
+        int n, el;
+        cin >> n;
+        int odd = 0, even = 0;
+        for(int i = 0; i < n; i++) {
+            cin >> el;
+            odd += (abs(el) % 2 == 1);
+            even += (abs(el) % 2 == 0);
+        }
+        vector<vector<vector<int>>> memo(n+1, vector<vector<int>>(n+1, vector<int>(2, -1)));
+        bool res = solve(odd, even, true, true, memo);
+        cout << (res ? "Alice" : "Bob") << endl;
+    }
+
+    return 0;
+}

problem-of-the-day/day13/Mortal Kombat Tower.cpp

@@ -0,0 +1,30 @@
+#include<iostream>
+#include <stdlib.h>
+#include <vector>
+using namespace std;
+#define int long long
+#define rep(i, a, b) for (int i = a; i < b; i++)
+
+void solve() {
+    int n;cin>>n;
+    vector<int>a(n+1);
+    rep(i,1,n+1)cin>>a[i];
+    vector<int>f(n+2,0);
+    vector<int>m(n+2,0);
+    if(a[n]==1)f[n]=1;
+    for(int i = n-1 ; i>=1 ; i--){
+        f[i] = min( m[i+2] + a[i] + a[i+1],m[i+1] + a[i]);
+        m[i] = min(f[i+1],f[i+2]);
+    }
+    cout<<f[1]<<'\n';
+}
+int32_t main() {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int t;
+  cin >> t;
+  while (t--) {
+    solve();
+  }
+  return 0;
+}

problem-of-the-day/day13/Rudolf and the Ugly String.cpp

@@ -0,0 +1,48 @@
+#include<iostream>
+#include <stdlib.h>
+#include <vector>
+using namespace std;
+#define int long long
+#define rep(i, a, b) for (int i = a; i < b; i++)
+
+///DP solution
+void solve() {
+    int n;string s;cin>>n>>s;
+    int i = n-2;
+    vector<int>ans(n+1,0);
+    for(int i = n-2; i>=0;i--){
+        if(s.substr(i,3)=="map" || s.substr(i,3)=="pie"){
+            ans[i] = 1ll + min(ans[i+1],min(ans[i+2],ans[i+3]));
+        }
+        else ans[i] = ans[i+1];
+    }
+    cout<<ans[0]<<'\n';
+}
+
+/// greedy
+void solve(){
+    int n;
+	cin >> n;
+	string s;
+	cin >> s;
+	vector<int> va;                 
+	for (string sul : {"mapie", "pie", "map"}) {
+		for (int pos = 0; (pos = s.find(sul, pos)) != string::npos;) {
+			s[pos + sul.length() / 2] = '?';
+			va.push_back(pos + sul.length() / 2);
+		}
+	}
+	cout << va.size() << endl;
+}
+
+
+int32_t main() {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int t;
+  cin >> t;
+  while (t--) {
+    solve();
+  }
+  return 0;
+}

problem-of-the-day/day13/YetnotherrokenKeoard.cpp

@@ -0,0 +1,51 @@
+#include<iostream>
+#include <stdlib.h>
+#include <vector>
+using namespace std;
+#define int long long
+#define rep(i, a, b) for (int i = a; i < b; i++)
+
+
+void solve() {
+    string s;cin>>s;
+    int n = s.size();
+    vector<bool>a(n,true);
+    int B=0,b=0;
+    char c;
+    for(int i = n-1; i>=0 ;i--){
+        c = s[i];
+        if(c=='b'){
+            a[i]=false;
+            b++;
+        }
+        else if(c=='B'){
+            a[i]=false;
+            B++;
+        }
+        else{
+            if('a'<=c && c<='z' && b>0){
+                a[i]=false;
+                b--;
+            }
+            else if('A'<=c && c<='Z' && B>0){
+                a[i]=false;
+                B--;
+            }
+        }
+    }
+    rep(i,0,n){
+        if(a[i])cout<<s[i];
+    }
+    cout<<'\n';
+}
+
+int32_t main() {
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+  int t;
+  cin >> t;
+  while (t--) {
+    solve();
+  }
+  return 0;
+}

problem-of-the-day/day13/dsa.md

@@ -14,7 +14,8 @@ After covering all the major data structures, we will now be focusing on few spe
 5. [Digit Queries](https://cses.fi/problemset/task/2431/):- Make sure to use long long in this problem. What happens when you use int. Also implement it in python. Why no such issue occurs there. What is the internal implementation of integers in python.
 
 ## Resources
-1. [Introduction to Dynamic Programming](https://cp-algorithms.com/dynamic_programming/intro-to-dp.html) 
+
+1. [Introduction to Dynamic Programming](https://cp-algorithms.com/dynamic_programming/intro-to-dp.html)
 2. [Greedy Algorithm](https://www.geeksforgeeks.org/greedy-algorithms/):- Prim's and Kruskal's Algorithm. Which is greedy ? What about Dijkstra ?
 
 **Note:** Solutions to [day12](../day12) are uploaded.