From 0cee2eb28f14410ccd674346396ee81499f7edba Mon Sep 17 00:00:00 2001
From: Abhinandan <93651229+AE-Hertz@users.noreply.github.com>
Date: Tue, 29 Oct 2024 13:49:01 +0530
Subject: [PATCH] feat: gift wrapping algo

---
 .../GiftWrappingAlgo.c                        | 71 +++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 Miscellaneous Algorithms/Gift Wrapping Algorithm/GiftWrappingAlgo.c

diff --git a/Miscellaneous Algorithms/Gift Wrapping Algorithm/GiftWrappingAlgo.c b/Miscellaneous Algorithms/Gift Wrapping Algorithm/GiftWrappingAlgo.c
new file mode 100644
index 00000000..31ffe6c2
--- /dev/null
+++ b/Miscellaneous Algorithms/Gift Wrapping Algorithm/GiftWrappingAlgo.c	
@@ -0,0 +1,71 @@
+// Gift Wrapping Algo
+
+#include <stdio.h>
+
+// Structure to represent a point
+typedef struct {
+    int x, y;
+} Point;
+
+// Function to find the orientation of the triplet (p, q, r)
+// Returns 0 if collinear, 1 if clockwise, and 2 if counterclockwise
+int orientation(Point p, Point q, Point r) {
+    int val = (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y);
+    if (val == 0) return 0;  // collinear
+    return (val > 0) ? 1 : 2; // clock or counter-clock wise
+}
+
+// Function to find the leftmost point
+Point findLeftmostPoint(Point points[], int n) {
+    Point leftmost = points[0];
+    for (int i = 1; i < n; i++) {
+        if (points[i].x < leftmost.x) {
+            leftmost = points[i];
+        }
+    }
+    return leftmost;
+}
+
+// Gift Wrapping Algorithm (Jarvis March)
+void giftWrap(Point points[], int n) {
+    if (n < 3) {
+        printf("Convex hull is not possible with less than 3 points.\n");
+        return;
+    }
+
+    // Initialize result (the convex hull)
+    Point hull[n];
+    int hullIndex = 0;
+
+    // Find the leftmost point
+    Point current = findLeftmostPoint(points, n);
+    do {
+        hull[hullIndex++] = current; // Add current point to the hull
+
+        // Search for a point 'next' such that orientation(current, next, points[i]) is counterclockwise
+        Point next = points[0];
+        for (int i = 1; i < n; i++) {
+            if (orientation(current, next, points[i]) == 2) {
+                next = points[i];
+            }
+        }
+
+        current = next; // Set next point as current
+    } while (current.x != hull[0].x || current.y != hull[0].y); // Loop until we reach the start point
+
+    // Print the convex hull
+    printf("Convex Hull:\n");
+    for (int i = 0; i < hullIndex; i++) {
+        printf("(%d, %d)\n", hull[i].x, hull[i].y);
+    }
+}
+
+// Main function
+int main() {
+    Point points[] = {{0, 3}, {2, 2}, {1, 1}, {2, 1}, {3, 0}, {0, 0}, {3, 3}};
+    int n = sizeof(points) / sizeof(points[0]);
+    
+    giftWrap(points, n);
+
+    return 0;
+}