organised 2024 year and added day4 in rust solution

2024/1/day1bothparts/part2.cpp

@@ -0,0 +1,36 @@
+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <algorithm>
+#include <cmath>
+
+int main() {
+    std::ifstream f("b");
+
+    std::vector<int> x;
+    std::vector<int> y;
+    int l, r;
+    
+    while (f >> l >> r) {
+        x.push_back(l);
+        y.push_back(r);
+    }
+
+    std::sort(x.begin(), x.end());
+    std::sort(y.begin(), y.end());
+ 
+    long t = 0;
+    int c = 0;
+    auto p = y.begin();
+    for (size_t i = 0; i < 4000000; i++) {
+	    auto b = std::lower_bound(p, y.end(), x[i]);
+	    auto u = std::upper_bound(p, y.end(), x[i]);
+	    int c = u - b;
+	    t += x[i] * c;
+	    p = b;
+    }
+
+    std::cout << t;
+
+    return 0;
+}