a very simple problem

2336-231129-pass/main.cpp

@@ -0,0 +1,36 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+class SmallestInfiniteSet {
+public:
+    const int length = 1010;
+    bool nums[1010];
+    SmallestInfiniteSet() {
+        for(int i = 0 ; i <length ;i++) nums[i] = 1; 
+    }
+    
+    int popSmallest() {
+        int i = 1;
+        while(nums[i]==0) i++;
+        nums[i] = 0;
+        return i; 
+    }
+    
+    void addBack(int num) {
+        nums[num] = 1; 
+    }
+};
+
+int main(){
+    SmallestInfiniteSet sol;
+
+    sol.addBack(2);
+    cout<<sol.popSmallest()<<endl;;
+    cout<<sol.popSmallest()<<endl;;
+    cout<<sol.popSmallest()<<endl;;
+    sol.addBack(1);
+    cout<<sol.popSmallest()<<endl;;
+    cout<<sol.popSmallest()<<endl;;
+    cout<<sol.popSmallest()<<endl;;
+    return 0;
+}