Merge pull request #1907 from Garavirod/feature/typescrypt-0417-solution

Create 0417-pacififc-atlantic-water-flow

Author: tahsintunan

Diff for: typescript/0417-pacific-atlantic-water-flow.ts

@@ -0,0 +1,73 @@
+/**
+ * Breath First Search implementation
+ * @param matrix 
+ * @param queue 
+ * @param visited 
+ */
+const bfs = (matrix: number[][], queue: number[][], visited: boolean[][]): void => {
+    let m = matrix.length, n = matrix[0].length;
+    let directions = [[1, 0], [-1, 0], [0, 1], [0, -1]];
+
+    while (queue.length > 0) {
+        const [qCordx, qCordy] = queue.shift()!;
+        for (let dir of directions) {
+            const x = qCordx + dir[0], y = qCordy + dir[1];
+            if (!(
+                x < 0 ||
+                y < 0 ||
+                x >= m ||
+                y >= n ||
+                visited[x][y] ||
+                matrix[x][y] < matrix[qCordx][qCordy])
+            ) {
+                visited[x][y] = true;
+                queue.push([x, y]);
+            }
+
+        }
+    }
+}
+
+/**
+ * Creates a Matrix NXM with false values
+ */
+const createMatrix = (n: number, m: number): boolean[][] =>
+    Array.from({ length: n }, () => Array.from({ length: m }, () => false));
+
+
+function pacificAtlantic(heights: number[][]): number[][] {
+    const ROWS = heights.length, COLS = heights[0].length;
+    let pacific: boolean[][] = createMatrix(ROWS, COLS);
+    let atlantic: boolean[][] = createMatrix(ROWS, COLS);
+    let pacQueue: number[][] = [];
+    let atlQueue: number[][] = [];
+    let results: number[][] = [];
+
+    // Set as 'true' Pacific edges
+    for (let i = 0; i < ROWS; i++) {
+        pacific[i][0] = true;
+        atlantic[i][COLS - 1] = true;
+        atlQueue.push([i, COLS - 1]);
+        pacQueue.push([i, 0]);
+    }
+    // Set as 'true' atlantic edges
+    for (let j = 0; j < COLS; j++) {
+        pacific[0][j] = true;
+        atlantic[ROWS - 1][j] = true;
+        atlQueue.push([ROWS - 1, j]);
+        pacQueue.push([0, j]);
+    }
+
+    // BFS
+    bfs(heights, pacQueue, pacific);
+    bfs(heights, atlQueue, atlantic);
+
+    // Verify intersections
+    for (let i = 0; i < ROWS; i++) {
+        for (let j = 0; j < COLS; j++) {
+            if (pacific[i][j] && atlantic[i][j]) results.push([i, j]);
+        }
+    }
+
+    return results;
+};