[ya-day1] swimmer problem WIP

lib/toGetClosestPoint/index.ts

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+import { toGetClosestPoint } from "./toGetClosestPoint";
+
+export default toGetClosestPoint;

lib/toGetClosestPoint/toGetClosestPoint.test.ts

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+import { describe, it, expect } from "vitest";
+import { toGetClosestPoint } from "./toGetClosestPoint.ts";
+
+describe("toGetClosestPoint", () => {
+  it("toGetClosestPoint equale NW", () => {
+    expect(toGetClosestPoint(-1, -2, 5, 3, -4, 6)).toBe("NW");
+  });
+
+  it("toGetClosestPoint equale N", () => {
+    expect(toGetClosestPoint(-1, -2, 5, 3, 4, 5)).toBe("N");
+  });
+
+  it("toGetClosestPoint equale NE", () => {
+    expect(toGetClosestPoint(-1, -2, 5, 3, 9, 3)).toBe("NE");
+  });
+
+  it("toGetClosestPoint equale E", () => {
+    expect(toGetClosestPoint(-1, -2, 5, 3, 7, 0)).toBe("E");
+  });
+
+  it("toGetClosestPoint equale SE", () => {
+    expect(toGetClosestPoint(-1, -2, 5, 3, 8, -4)).toBe("SE");
+  });
+
+  it("toGetClosestPoint equale S", () => {
+    expect(toGetClosestPoint(-1, -2, 5, 3, 2, -4)).toBe("S");
+  });
+
+  it("toGetClosestPoint equale SW", () => {
+    expect(toGetClosestPoint(-1, -2, 5, 3, -5, -2)).toBe("SW");
+  });
+
+  it("toGetClosestPoint equale W", () => {
+    expect(toGetClosestPoint(-1, -2, 5, 3, -5, 2)).toBe("W");
+  });
+});

lib/toGetClosestPoint/toGetClosestPoint.ts

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+type Direction = "N" | "E" | "S" | "W" | "NW" | "NE" | "SW" | "SE";
+export function toGetClosestPoint(
+  x1: number,
+  y1: number,
+  x2: number,
+  y2: number,
+  sx: number,
+  sy: number,
+) {
+  let direction: Direction = "N";
+
+  const sectors: Record<Direction, number[]> = {
+    NW: [x1, y2],
+    N: [x1, y2],
+    NE: [x2, y2],
+    E: [x2, y2],
+    SE: [x2, y1],
+    S: [x1, y1],
+    SW: [x1, y1],
+    W: [x1, y2],
+  };
+
+  for (let key in sectors) {
+    const [x, y] = sectors[key];
+
+    if (sx <= x && sy >= y) {
+      direction = "NW";
+      break;
+    }
+    if (sx >= x && sy > y && sx <= x2) {
+      direction = "N";
+      break;
+    }
+    if (sx >= x && sy >= y) {
+      direction = "NE";
+      break;
+    }
+
+    if (sx >= x && sy <= y && sy >= y1) {
+      direction = "E";
+      break;
+    }
+
+    if (sx >= x && sy <= y && sx <= x2) {
+      direction = "S";
+      break;
+    }
+
+    if (sx >= x && sy <= y) {
+      direction = "SE";
+      break;
+    }
+
+    if (sy <= y && sx <= x) {
+      direction = "SW";
+      break;
+    }
+
+    if (sy <= y2 && sy >= y1 && sx <= x) {
+      direction = "W";
+      break;
+    }
+  }
+
+  return direction;
+}