i should provide the correct input: (f,k,z) to have the program print the sentence: Exactly! Good Job. The input should satisfy the 3 methods Here we have 3 methods, each one either succeds or fails (if failed it prints: nope) I tried to execute metallica and aerosmith method by hand and solve equations but am stuck there...

#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
static int64_t ac_dc[] = {10143, 54893, 47109, 24350, 17669, 82062};
const static int N = sizeof(ac_dc) / sizeof(*ac_dc);
static void fail() {
    puts("Nope!");
    exit(EXIT_FAILURE);
}
static void linkin_park(int64_t t, int64_t v, int64_t s) {
    if(t - s / 7   3 * v / 11) fail();
}
static void metallica(int o, int64_t j) {
    int64_t g = j;
    for(; o < N;   o) {
        if((o % 2) == 0) continue;
        g  = ac_dc[o];
    }
    if(g != 94857) fail();
}
static void aerosmith(int d, int64_t n) {
    if(d < N) {
        if(d % 2)
            aerosmith(  d, n);
        else
            aerosmith(d   1, n * ac_dc[d]);
    } else if(n != 540151794)
        fail();
}
int main() {
    int64_t f, k, z;
    printf("Please enter the right three numbers: ");
    fflush(stdout);
    if(scanf("%" SCNd64 " %" SCNd64 " %" SCNd64, &f, &k, &z) != 3) fail();
    ac_dc[0] = f;
    ac_dc[5] = k;
    ac_dc[4] = z;
    metallica(0, 14041);
    aerosmith(1, 9);
    linkin_park(f, k, z);
    puts("Exactly! Good job.");
}

CodePudding user response：

Think of it as system of 3 equations with 3 unknowns: f, k, z.

The program assigns these values to a global array

static int64_t ac_dc[] = {f, 54893, 47109, 24350, z, k}; // conceptually

The linkin_park function is basically an equation of 3 variables:

f - z/7   3*k/11 = 0

We'll use it at the end to find the last unknown, given the other two.

metallica is "easier":

g   ac_dc[1]   ac_dc[3]   ac_dc[5] = 94857
14041   54893   24350   k = 94857
k = 1573

aerosmith is more challenging, but if we trace the parameters of the recursive calls:

z = 540151794 / 423981

That's enough to find all the unknowns.