From 4e148d3c1377a3162998b95e990ced1debf2296b Mon Sep 17 00:00:00 2001
From: Dennis Kobert <dennis@kobert.dev>
Date: Sun, 22 Dec 2019 17:14:42 +0100
Subject: Prune solver by ommitting some permutations

---
 src/solvers/intuitive.rs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/solvers/intuitive.rs b/src/solvers/intuitive.rs
index 77f63e5..0899906 100644
--- a/src/solvers/intuitive.rs
+++ b/src/solvers/intuitive.rs
@@ -100,6 +100,7 @@ impl<T: num::PrimInt> NormalSolver<T> {
     }
 
     fn permute(&mut self, up: usize, index: usize, numbers: &[u32]) {
+        let chunk = self.permutations.len() / self.h as usize;
         if index as usize == numbers.len() {
             //println!("checking {:?}", numbers);
             if self.check_perm(&numbers) {
@@ -108,9 +109,9 @@ impl<T: num::PrimInt> NormalSolver<T> {
             return;
         }
         let mut new_num = Vec::from(numbers);
-        for i in numbers[index as usize] as usize..up {
+        for i in numbers[index as usize] as usize..((index + 1) * chunk) {
             for n in (index + 1)..numbers.len() {
-                new_num[n] = (n * (self.permutations.len() / self.h as usize)) as u32;
+                new_num[n] = (n * chunk) as u32;
             }
             self.permute(up, index + 1, &new_num);
             new_num[index] += 1;
@@ -124,7 +125,8 @@ impl<T: num::PrimInt> NormalSolver<T> {
         let mut sums = vec![self.w; self.w as usize];
         for (i, num) in nums.iter().enumerate() {
             let mut sum = 0;
-            for n in self.permutations[*num as usize][..(self.n - 1) as usize].iter() {
+            for n in self.permutations[*num as usize][..(self.n - 1 - (self.n & 1)) as usize].iter()
+            {
                 sum += *n as usize;
                 if sums[sum - 1] != self.w {
                     return false;
-- 
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