From 5ef0986e98ef021e5ce2f46cdaba244c2c51bc4c Mon Sep 17 00:00:00 2001
From: Tyge Løvset <tylo@norceresearch.no>
Date: Mon, 13 Mar 2023 12:40:07 +0100
Subject: Fixed bug and improved generic c_eraseremove_if().

---
 misc/examples/triples.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

(limited to 'misc')

diff --git a/misc/examples/triples.c b/misc/examples/triples.c
index 4783d603..aac7967a 100644
--- a/misc/examples/triples.c
+++ b/misc/examples/triples.c
@@ -4,12 +4,12 @@
 #include <stdio.h>
 
 void triples_vanilla(int n) {
-    for (int i = 1, c = 1;; ++c) {
+    for (int i = 5, c = 1;; ++c) {
         for (int a = 1; a < c; ++a) {
-            for (int b = a; b < c; ++b) {
-                if (a*a + b*b == c*c) {
-                    printf("{%d, %d, %d},\n", a, b, c);
-                    if (++i > n) goto done;
+            for (int b = a + 1; b < c; ++b) {
+                if ((int64_t)a*a + (int64_t)b*b == (int64_t)c*c) {
+                    if (i++ == n) goto done;
+                    printf("{%d, %d, %d}\n", a, b, c);
                 }
             }
         }
@@ -25,10 +25,10 @@ struct triples {
 
 bool triples_next(struct triples* I) {
     cco_begin(I);
-        for (I->c = 1;; ++I->c) {
+        for (I->c = 5;; ++I->c) {
             for (I->a = 1; I->a < I->c; ++I->a) {
-                for (I->b = I->a; I->b < I->c; ++I->b) {
-                    if (I->a*I->a + I->b*I->b == I->c*I->c) {
+                for (I->b = I->a + 1; I->b < I->c; ++I->b) {
+                    if ((int64_t)I->a*I->a + (int64_t)I->b*I->b == (int64_t)I->c*I->c) {
                         if (I->n-- == 0) cco_return;
                         cco_yield(true);
                     }
@@ -36,9 +36,18 @@ bool triples_next(struct triples* I) {
             }
         }
         cco_final:
+        puts("done");
     cco_end(false);
 }
 
+int gcd(int a, int b) {
+    while (b) {
+        int t = a % b;
+        a = b;
+        b = t;
+    }
+    return a;
+}
 
 int main()
 {
@@ -47,8 +56,14 @@ int main()
 
     puts("\nCoroutine triples:");
     struct triples t = {INT32_MAX};
+    int n = 0;
+
     while (triples_next(&t)) {
-        if (t.c < 100) printf("{%d, %d, %d},\n", t.a, t.b, t.c);
-        else cco_stop(&t);
+        if (gcd(t.a, t.b) > 1)
+            continue;
+        if (t.c < 1000)
+            printf("%d: {%d, %d, %d}\n", ++n, t.a, t.b, t.c);
+        else
+            cco_stop(&t);
     }
 }
-- 
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