update: Apr23 sliding windows

daily/Apr22.cpp

@@ -0,0 +1,44 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Solution {
+  int dfs(int i, vector<int>& nums, vector<int>& memo) {
+    if (i == 0) {  // finish
+      return 1;
+    }
+    int& res = memo[i];  // reference
+    if (res != -1) {
+      return res;
+    }
+    res = 0;
+
+    for (int x : nums) {
+      if (x <= i) {
+        res += dfs(i - x, nums, memo);
+      }
+    }
+    return res;
+  }
+
+ public:
+  int combinationSum4(vector<int>& nums, int target) {
+    vector<int> memo(target + 1, -1);  // -1 not computed before
+
+    return dfs(target, nums, memo);
+  }
+
+  int combinationSum4Op(vector<int>& nums, int target) {
+    // use unsigned to make overflow still returns normally
+    // for the overflow dsata,
+    vector<unsigned> f(target + 1);
+    f[0] = 1;
+    for (int i = 1; i <= target; i++) {
+      for (int x : nums) {
+        if (x <= i) {
+          f[i] += f[i - x];
+        }
+      }
+    }
+    return f[target];
+  }
+};

daily/Apr23.cpp

@@ -0,0 +1,40 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Solution {
+ public:
+  int maxSatisfied(vector<int>& customers, vector<int>& grumpy, int minutes) {
+    int s[2]{}, max_s1 = 0;
+    for (int i = 0; i < customers.size(); i++) {
+      s[grumpy[i]] += customers[i];
+      if (i < minutes - 1) {  // windows size less than minutes
+        continue;
+      }
+      max_s1 = max(max_s1, s[1]);
+      // leftmost goes out of window
+      s[1] -= grumpy[i - minutes + 1] ? customers[i - minutes + 1] : 0;
+    }
+    return s[0] + max_s1;
+  }
+
+  int maxSatisfied1(vector<int>& customers, vector<int>& grumpy, int minutes) {
+    int total = 0;
+    int n = customers.size();
+    for (int i = 0; i < n; i++) {
+      if (grumpy[i] == 0) {
+        total += customers[i];
+      }
+    }
+    int increase = 0;
+    for (int i = 0; i < minutes; i++) {
+      increase += customers[i] * grumpy[i];
+    }
+    int maxIncrease = increase;
+    for (int i = minutes; i < n; i++) {
+      increase = increase - customers[i - minutes] * grumpy[i - minutes] +
+                 customers[i] * grumpy[i];
+      maxIncrease = max(maxIncrease, increase);
+    }
+    return total + maxIncrease;
+  }
+};