some dp problems

CSES - CSES Problem Set/Coin_Combinations_I.cpp

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+//  Coin Combinations I
+
+#include<bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+const int MOD = 1e9 + 7;
+ll dp[(int)1e6 + 1];
+
+int main() {
+    int n; int x; cin >> n >> x;
+    dp[0] = 1;
+    vector<int> in(n);
+    for (int i = 0; i < n; i++) cin >> in[i];
+    for (int i = 0; i <= x; ++i) {
+        for (int j = 0; j < n; j++) {
+            if (in[j] <= i) {
+                dp[i] += dp[i - in[j]];
+                dp[i] %= MOD;
+            }
+        }
+    }
+    cout << dp[x] << endl;
+    return 0;
+}

CSES - CSES Problem Set/Coin_Combinations_II.cpp

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+//  Coin Combinations II
+
+#include<bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+const int MOD = 1e9 + 7;
+ll dp[(int)1e6 + 1];
+
+int main() {
+    dp[0] = 1;
+    int n, x;
+    cin >> n >> x;
+    for (int i{}; i < n; i++) {
+        int c; cin >> c;
+        for (int j = c; j <= x; j++) {
+            dp[j] += dp[j-c];
+            dp[j] %= MOD;
+        }
+    }
+    cout << dp[x] << endl;
+    return 0;
+}

CSES - CSES Problem Set/Dice_Combinations.cpp

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+//  Dice Combinations
+
+#include<bits/stdc++.h>
+
+using namespace std;
+using ll = long long;
+
+const ll N = 1e6;
+const ll MOD = 1e9 + 7;
+
+ll ways[N + 1];
+
+int main() {
+    ll n; cin >> n;
+    ways[0] = 1;
+    for (ll i = 1; i <= n; i++) {
+        for (ll j = 1; j <= 6 && j <= i; j++) {
+            ways[i] = (ways[i] + (ways[i - j])) % MOD;
+        }
+    }
+    cout << ways[n];
+}

CSES - CSES Problem Set/Minimizing_Coins.cpp

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+//  Minimizing Coins
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+int main() {
+    int n, x;
+    cin >> n >> x;
+    vector<int> dp(x + 1, INT_MAX - 5);
+    dp[0] = 0;
+    for (int i{}; i < n; i++) {
+        int c; cin >> c;
+        for (int j = c; j <= x; j++) {
+            if (j >= c) {
+                dp[j] = min(dp[j - c] + 1, dp[j]);
+            }
+        }
+    }
+    if (dp[x] != INT_MAX - 5) cout << dp[x] << endl;
+    else cout << -1 << endl;
+    return 0;
+}

CSES - CSES Problem Set/Removing_Digits.cpp

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+//  Removing Digits
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+int dp[(int)1e6 + 1];
+
+
+int solve(int n) {
+    if (dp[n]) return dp[n];
+    int count = INT_MAX;
+    if (n == 0) return 0;
+    for (int i = 1; i <= 10 * n; i*= 10) {
+        int remove = (n / i) - (n / (10 * i)) * 10;
+        if (!remove) continue;
+        count = min(count, 1 + solve(n - remove));
+    }
+    dp[n] = count;
+    return count;
+}
+
+
+int main() {
+    int n; cin >> n;
+    cout << solve(n) << endl;
+    return 0;
+}