Data commit

Task/Display-a-linear-combination/D/display-a-linear-combination.d

@@ -0,0 +1,53 @@
+import std.array;
+import std.conv;
+import std.format;
+import std.math;
+import std.stdio;
+
+string linearCombo(int[] c) {
+    auto sb = appender!string;
+    foreach (i, n; c) {
+        if (n==0) continue;
+        string op;
+        if (n < 0) {
+            if (sb.data.empty) {
+                op = "-";
+            } else {
+                op = " - ";
+            }
+        } else if (n > 0) {
+            if (!sb.data.empty) {
+                op = " + ";
+            }
+        }
+        auto av = abs(n);
+        string coeff;
+        if (av != 1) {
+            coeff = to!string(av) ~ "*";
+        }
+        sb.formattedWrite("%s%se(%d)", op, coeff, i+1);
+    }
+    if (sb.data.empty) {
+        return "0";
+    }
+    return sb.data;
+}
+
+void main() {
+    auto combos = [
+        [1, 2, 3],
+        [0, 1, 2, 3],
+        [1, 0, 3, 4],
+        [1, 2, 0],
+        [0, 0, 0],
+        [0],
+        [1, 1, 1],
+        [-1, -1, -1],
+        [-1, -2, 0, -3],
+        [-1],
+    ];
+    foreach (c; combos) {
+        auto arr = c.format!"%s";
+        writefln("%-15s  ->  %s", arr, linearCombo(c));
+    }
+}