Add test: Send More Money.

sendmoremoney_carry: 154 guesses.
sendmoremoney_naive: 633681 guesses.

tests/sendmoremoney.rs

@@ -0,0 +1,84 @@
+//! Send More Money.
+//!
+//! https://en.wikipedia.org/wiki/Verbal_arithmetic
+
+extern crate puzzle_solver;
+
+use puzzle_solver::{Puzzle,Solution,VarToken};
+
+fn make_send_more_money() -> (Puzzle, Vec<VarToken>) {
+    let mut sys = Puzzle::new();
+    let vars = sys.new_vars_with_candidates_1d(8, &[0,1,2,3,4,5,6,7,8,9]);
+    let (s, e, n, d) = (vars[0], vars[1], vars[2], vars[3]);
+    let (m, o, r, y) = (vars[4], vars[5], vars[6], vars[7]);
+
+    sys.remove_candidates(s, &[0]);
+    sys.remove_candidates(m, &[0]);
+
+    sys.all_different(&vars);
+
+    let send = 1000 * s + 100 * e + 10 * n + d;
+    let more = 1000 * m + 100 * o + 10 * r + e;
+    let money = 10000 * m + 1000 * o + 100 * n + 10 * e + y;
+    sys.equals(send + more, money);
+
+    (sys, vars)
+}
+
+fn print_send_more_money(dict: &Solution, vars: &Vec<VarToken>) {
+    let (s, e, n, d) = (vars[0], vars[1], vars[2], vars[3]);
+    let (m, o, r, y) = (vars[4], vars[5], vars[6], vars[7]);
+
+    println!("   {} {} {} {}", dict[s], dict[e], dict[n], dict[d]);
+    println!(" + {} {} {} {}", dict[m], dict[o], dict[r], dict[e]);
+    println!("----------");
+    println!(" {} {} {} {} {}", dict[m], dict[o], dict[n], dict[e], dict[y]);
+}
+
+fn verify_send_more_money(dict: &Solution, vars: &Vec<VarToken>) {
+    let (s, e, n, d) = (vars[0], vars[1], vars[2], vars[3]);
+    let (m, o, r, y) = (vars[4], vars[5], vars[6], vars[7]);
+
+    assert_eq!(dict[o], 0);
+    assert_eq!(dict[m], 1);
+    assert_eq!(dict[y], 2);
+    assert_eq!(dict[e], 5);
+    assert_eq!(dict[n], 6);
+    assert_eq!(dict[d], 7);
+    assert_eq!(dict[r], 8);
+    assert_eq!(dict[s], 9);
+}
+
+#[test]
+fn sendmoremoney_carry() {
+    let carry = [0,1];
+
+    let (mut sys, vars) = make_send_more_money();
+    let (s, e, n, d) = (vars[0], vars[1], vars[2], vars[3]);
+    let (m, o, r, y) = (vars[4], vars[5], vars[6], vars[7]);
+    let c1 = sys.new_var_with_candidates(&carry);
+    let c2 = sys.new_var_with_candidates(&carry);
+    let c3 = sys.new_var_with_candidates(&carry);
+    sys.intersect_candidates(m, &carry); // c4 == m.
+
+    sys.equals(     d + e, 10 * c1 + y);
+    sys.equals(c1 + n + r, 10 * c2 + e);
+    sys.equals(c2 + e + o, 10 * c3 + n);
+    sys.equals(c3 + s + m, 10 *  m + o);
+
+    let dict = sys.solve_unique().expect("solution");
+    println!("sendmoremoney_carry: {} guesses", sys.num_guesses());
+    print_send_more_money(&dict, &vars);
+    verify_send_more_money(&dict, &vars);
+}
+
+/*
+#[test]
+fn sendmoremoney_naive() {
+    let (mut sys, vars) = make_send_more_money();
+    let dict = sys.solve_unique().expect("solution");
+    println!("sendmoremoney_naive: {} guesses", sys.num_guesses());
+    print_send_more_money(&dict, &vars);
+    verify_send_more_money(&dict, &vars);
+}
+*/