Compute ADC Voltage Scale

#include <iostream>
#include <cstdint>

using namespace std;

// Compile-time ADC scale computation using integer truncation
constexpr int32_t computeScale(int32_t maxAdc, int32_t maxVoltage_mV) {
    // Convert millivolts to microvolts, then divide by ADC resolution
    // (3300 * 1000) / 4095 = 805.86... -> truncated to 805
    return (maxVoltage_mV * 1000) / maxAdc;
}

// Compile-time microvolts-per-count scale factor
constexpr int32_t SCALE_UV = computeScale(4095, 3300);

int main() {
    int32_t x;
    if (!(cin >> x)) return 0;

    // Runtime ADC-to-voltage conversion
    // Max result: 4095 * 805 = 3,296,475 (fits in int32_t)
    int32_t voltage_uv = x * SCALE_UV;

    cout << voltage_uv;
    return 0;
}

Solving Approach