- Added guest contributions by Laurent Rosenfeld.

3 files changed, 68 insertions, 0 deletions

diff --git a/challenge-172/laurent-rosenfeld/c/ch-2.c b/challenge-172/laurent-rosenfeld/c/ch-2.c
new file mode 100644
index 0000000000..e617c3daf3
--- /dev/null
+++ b/challenge-172/laurent-rosenfeld/c/ch-2.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int compare_int(const void *a,const void *b) {
+    int *x = (int *) a;
+    int *y = (int *) b;
+    return *x - *y;
+}
+
+float median (int count, int m[]) {
+    if (count % 2) {
+        return 1.0 * m[(count -1)/2];
+    } else {
+        return (m[count/2 -1] + m[count/2])/2.0;
+    }
+}
+
+int main() {
+    int moons[] = {0, 0, 1, 2, 63, 61, 27, 13};
+    int size = sizeof(moons)/sizeof(*moons);
+    qsort (moons, size, sizeof(*moons), compare_int);
+    float min = 1.0 * moons[0];
+    float med = median(size, moons);
+    int half = (int)size/2;
+    float first_q = median(half, moons);
+    float last_q = median(half, moons + 4);
+    float max = 1.0 * moons[size - 1];
+    printf ("%.2f %.2f %.2f %.2f %.2f", min, first_q, med, last_q, max);
+    return 0;
+}
diff --git a/challenge-172/laurent-rosenfeld/ring/ch-2.ring b/challenge-172/laurent-rosenfeld/ring/ch-2.ring
new file mode 100644
index 0000000000..48ce135550
--- /dev/null
+++ b/challenge-172/laurent-rosenfeld/ring/ch-2.ring
@@ -0,0 +1,18 @@
+moons = [0, 0, 1, 2, 63, 61, 27, 13]
+see summary(sort(moons))
+
+func summary(n)
+    min = n[1]
+    max = n[len(n)]
+    size = len(n)
+    med = median(1, size, n)
+    first_q =  median(1, size/2, n)
+    last_q = median(size/2 +1, size, n)
+    return [min, first_q, med, last_q, max]
+
+func median(low, high, n)
+    if (high + low) % 2 = 0
+        return n[low + (high - low + 1)/2]
+    else
+        return (n[low + (high - low + 1)/2] + n[low + (high - low + 1)/2 - 1]) / 2.0
+    ok
diff --git a/challenge-172/laurent-rosenfeld/ruby/ch-2.rb b/challenge-172/laurent-rosenfeld/ruby/ch-2.rb
new file mode 100644
index 0000000000..b05e88740d
--- /dev/null
+++ b/challenge-172/laurent-rosenfeld/ruby/ch-2.rb
@@ -0,0 +1,20 @@
+def median(n)
+    size = n.length
+    if size %2 != 0
+        n[(size + 1) / 2]
+    else
+        (n[size/2] + n[size/2 + 1]) / 2.0
+    end
+end
+
+def summary(n)
+    min = n[0]
+    max = n[-1]
+    med = median(n)
+    first_q = median( n.select { |i| i < med })
+    last_q = median( n.select { |i| i > med })
+    return min, first_q, med, last_q, max
+end
+
+moons = [0, 0, 1, 2, 63, 61, 27, 13]
+print summary(moons.sort), "\n"