speedup

encse · encse · commit cf7450f9f67d · 2021-12-10T12:16:00.000+01:00
diff --git a/2015/Day24/Solution.cs b/2015/Day24/Solution.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Immutable;
 using System.Collections.Generic;
 using System.Linq;
 
@@ -15,36 +16,34 @@ int[] Parse(string input) =>
         input.Split("\n").Select(int.Parse).ToArray();
 
     long Solve(int[] nums, int groups) {
-        var minLength = int.MaxValue;
-        var min = long.MaxValue;
-        foreach (var part in Pick(nums, 0, nums.Sum() / groups)) {
-            if (part.c < minLength) {
-                minLength = part.c;
-                min = part.mul;
-            } else if (part.c == minLength) {
-                min = Math.Min(min, part.mul);
+        var mul = (ImmutableList<int> l) => l.Aggregate(1L, (m, x) => m*x);
+
+        for(var i =0;i<nums.Length;i++) {
+            var parts = Pick(nums, i, 0, nums.Sum() / groups);
+            if (parts.Any()){
+                return parts.Select(mul).Min();
             }
         }
-        return min;
+        throw new Exception();
     }
     
-    IEnumerable<(int c, long mul)> Pick(int[] nums, int i, int sum) {
+    IEnumerable<ImmutableList<int>> Pick(int[] nums, int count, int i, int sum) {
         if (sum == 0) {
-            yield return (0, 1);
+            yield return ImmutableList.Create<int>();
             yield break;
         }
 
-        if (sum < 0 || i >= nums.Length){
+        if (count < 0 || sum < 0 || i >= nums.Length) {
             yield break;
         }
         
         if (nums[i] <= sum) {
-            foreach (var x in Pick(nums, i + 1, sum - nums[i])) {
-                yield return (x.c + 1, x.mul * nums[i]);
+            foreach (var x in Pick(nums, count-1, i + 1, sum - nums[i])) {
+                yield return x.Add(nums[i]);
             }
         }
 
-        foreach (var x in Pick(nums, i + 1, sum)) {
+        foreach (var x in Pick(nums, count, i + 1, sum)) {
             yield return x;
         }
     }

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,5 @@`
`1`	`1`	`using System;`
	`2`	`+using System.Collections.Immutable;`
`2`	`3`	`using System.Collections.Generic;`
`3`	`4`	`using System.Linq;`
`4`	`5`
`@@ -15,36 +16,34 @@ int[] Parse(string input) =>`
`15`	`16`	`input.Split("\n").Select(int.Parse).ToArray();`
`16`	`17`
`17`	`18`	`long Solve(int[] nums, int groups) {`
`18`		`- var minLength = int.MaxValue;`
`19`		`- var min = long.MaxValue;`
`20`		`- foreach (var part in Pick(nums, 0, nums.Sum() / groups)) {`
`21`		`- if (part.c < minLength) {`
`22`		`- minLength = part.c;`
`23`		`- min = part.mul;`
`24`		`- } else if (part.c == minLength) {`
`25`		`- min = Math.Min(min, part.mul);`
	`19`	`+ var mul = (ImmutableList<int> l) => l.Aggregate(1L, (m, x) => m*x);`
	`20`	`+`
	`21`	`+ for(var i =0;i<nums.Length;i++) {`
	`22`	`+ var parts = Pick(nums, i, 0, nums.Sum() / groups);`
	`23`	`+ if (parts.Any()){`
	`24`	`+ return parts.Select(mul).Min();`
`26`	`25`	`}`
`27`	`26`	`}`
`28`		`- return min;`
	`27`	`+ throw new Exception();`
`29`	`28`	`}`
`30`	`29`
`31`		`- IEnumerable<(int c, long mul)> Pick(int[] nums, int i, int sum) {`
	`30`	`+ IEnumerable<ImmutableList<int>> Pick(int[] nums, int count, int i, int sum) {`
`32`	`31`	`if (sum == 0) {`
`33`		`- yield return (0, 1);`
	`32`	`+ yield return ImmutableList.Create<int>();`
`34`	`33`	`yield break;`
`35`	`34`	`}`
`36`	`35`
`37`		`- if (sum < 0 \|\| i >= nums.Length){`
	`36`	`+ if (count < 0 \|\| sum < 0 \|\| i >= nums.Length) {`
`38`	`37`	`yield break;`
`39`	`38`	`}`
`40`	`39`
`41`	`40`	`if (nums[i] <= sum) {`
`42`		`- foreach (var x in Pick(nums, i + 1, sum - nums[i])) {`
`43`		`- yield return (x.c + 1, x.mul * nums[i]);`
	`41`	`+ foreach (var x in Pick(nums, count-1, i + 1, sum - nums[i])) {`
	`42`	`+ yield return x.Add(nums[i]);`
`44`	`43`	`}`
`45`	`44`	`}`
`46`	`45`
`47`		`- foreach (var x in Pick(nums, i + 1, sum)) {`
	`46`	`+ foreach (var x in Pick(nums, count, i + 1, sum)) {`
`48`	`47`	`yield return x;`
`49`	`48`	`}`
`50`	`49`	`}`