* Added a small Condorcet voting program.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/research@2284 92316355-f0b4-4df1-b90c-862c8a59935f

2008-displacement/.gitignore

@@ -4,3 +4,4 @@ main
 *.log
 *.pdf
 xy2d
+vote

2008-displacement/Makefile

@@ -1,11 +1,14 @@
-all: main xy2d
+all: main xy2d vote
 
 xy2d: xy2d.c
 	$(CC) -W -Wall $^ -o $@
 
+vote: vote.c
+	$(CC) -W -Wall $^ -o $@
+
 main: main.c
 	$(CC) -Wall -O3 -funroll-loops -ffast-math -W -Wall $^ -o $@ $$(pkg-config --cflags --libs sdl) -lSDL_image -lm
 
 clean:
-	rm -f xy2d main
+	rm -f xy2d vote main
 

2008-displacement/vote.c

@@ -0,0 +1,124 @@
+/* Quick voting software.
+ * Usage: 
+ *   vote <file1> <file2> ...
+ * File format:
+ *   <key1> <value1>
+ *   <key1> <value1>
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define MAXLEN 20
+#define MAXITEMS 2000
+
+static char *items[MAXITEMS];
+static int nitems;
+
+static int *matrix;
+
+static int lookup(char const *str)
+{
+    int i;
+
+    for(i = 0; i < nitems; i++)
+        if(!strcmp(str, items[i]))
+            return i;
+
+    return -1;
+}
+
+static int record(char const *str)
+{
+    int n = lookup(str);
+
+    if(n >= 0)
+        return n;
+
+    items[nitems] = strdup(str);
+    return nitems++;
+}
+
+static void recordfile(char const *file)
+{
+    char buf[MAXLEN];
+    FILE *f;
+    float val;
+
+    f = fopen(file, "r");
+    if(!f)
+        return;
+    while(!feof(f))
+    {
+        fscanf(f, "%s %g", buf, &val);
+        record(buf);
+    }
+    fclose(f);
+}
+
+static void readfile(char const *file)
+{
+    float values[MAXITEMS];
+    char buf[MAXLEN];
+    FILE *f;
+    float val;
+    int n, i, j;
+
+    f = fopen(file, "r");
+    if(!f)
+        return;
+    while(!feof(f))
+    {
+        fscanf(f, "%s %g", buf, &val);
+        n = lookup(buf);
+        values[n] = val;
+    }
+    fclose(f);
+
+    for(j = 0; j < nitems; j++)
+        for(i = j + 1; i < nitems; i++)
+            if(values[i] < values[j])
+                matrix[j * nitems + i]++;
+            else if(values[i] > values[j])
+                matrix[i * nitems + j]++;
+}
+
+static void solvematrix(void)
+{
+    int wins[MAXITEMS];
+    int i, j;
+
+    memset(wins, 0, MAXITEMS * sizeof(int));
+
+    for(j = 0; j < nitems; j++)
+        for(i = j + 1; i < nitems; i++)
+        {
+            if(matrix[j * nitems + i] > matrix[i * nitems + j])
+                wins[i]++;
+            else
+                wins[j]++;
+        }
+
+    for(i = 0; i < nitems; i++)
+        printf("%s (%i): %i wins\n", items[i], i, wins[i]);
+}
+
+int main(int argc, char *argv[])
+{
+    int i;
+
+    for(i = 1; i < argc; i++)
+        recordfile(argv[i]);
+
+    matrix = malloc(nitems * nitems * sizeof(int));
+    memset(matrix, 0, nitems * nitems * sizeof(int));
+
+    for(i = 1; i < argc; i++)
+        readfile(argv[i]);
+
+    solvematrix();
+
+    return 0;
+}
+