Initial data commit

Task/Sorting-algorithms-Heapsort/C/sorting-algorithms-heapsort.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+
+int max (int *a, int n, int i, int j, int k) {
+    int m = i;
+    if (j < n && a[j] > a[m]) {
+        m = j;
+    }
+    if (k < n && a[k] > a[m]) {
+        m = k;
+    }
+    return m;
+}
+
+void downheap (int *a, int n, int i) {
+    while (1) {
+        int j = max(a, n, i, 2 * i + 1, 2 * i + 2);
+        if (j == i) {
+            break;
+        }
+        int t = a[i];
+        a[i] = a[j];
+        a[j] = t;
+        i = j;
+    }
+}
+
+void heapsort (int *a, int n) {
+    int i;
+    for (i = (n - 2) / 2; i >= 0; i--) {
+        downheap(a, n, i);
+    }
+    for (i = 0; i < n; i++) {
+        int t = a[n - i - 1];
+        a[n - i - 1] = a[0];
+        a[0] = t;
+        downheap(a, n - i - 1, 0);
+    }
+}
+
+int main () {
+    int a[] = {4, 65, 2, -31, 0, 99, 2, 83, 782, 1};
+    int n = sizeof a / sizeof a[0];
+    int i;
+    for (i = 0; i < n; i++)
+        printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
+    heapsort(a, n);
+    for (i = 0; i < n; i++)
+        printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
+    return 0;
+}