create dev channel

zeta/c/completed/17387.c

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+typedef long long LL;
+
+int ccw(int x1, int y1, int x2, int y2, int x3, int y3) {
+    LL s = (LL) (x2 - x1) * (LL) (y3 - y1) - (LL) (y2 - y1) * (LL) (x3 - x1);
+    if (s > 0) return 1;
+    if (s < 0) return -1;
+    return 0;
+}
+
+int compare_leq(int x1, int y1, int x2, int y2) {
+    if (x1 == x2) {
+        return y1 <= y2;
+    }
+    return x1 <= x2;
+}
+
+int isIntersect(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4) {
+    int d1 = ccw(x1, y1, x2, y2, x3, y3);
+    int d2 = ccw(x1, y1, x2, y2, x4, y4);
+    int d3 = ccw(x3, y3, x4, y4, x1, y1);
+    int d4 = ccw(x3, y3, x4, y4, x2, y2);
+
+    int c1 = d1 * d2;
+    int c2 = d3 * d4;
+
+    if (c1 == 0 && c2 == 0) {
+        if (compare_leq(x2, y2, x1, y1)) {
+            int temp = x1;
+            x1 = x2;
+            x2 = temp;
+            temp = y1;
+            y1 = y2;
+            y2 = temp;
+        }
+        if (compare_leq(x4, y4, x3, y3)) {
+            int temp = x3;
+            x3 = x4;
+            x4 = temp;
+            temp = y3;
+            y3 = y4;
+            y4 = temp;
+        }
+        return (compare_leq(x1, y1, x4, y4) &&
+                compare_leq(x3, y3, x2, y2));
+    }
+
+    return c1 <= 0 && c2 <= 0;
+}
+
+int main() {
+    int x1, y1, x2, y2;
+    int x3, y3, x4, y4;
+    scanf("%d %d %d %d", &x1, &y1, &x2, &y2);
+    scanf("%d %d %d %d", &x3, &y3, &x4, &y4);
+
+    printf("%d\n", isIntersect(x1, y1, x2, y2, x3, y3, x4, y4));
+    return 0;
+}