https://leetcode.cn/problems/shortest-bridge/

Author: masx200

README.md

@@ -45,6 +45,8 @@ Step 2. Add the dependency
 
 <summary>展开查看</summary>
 
+https://leetcode.cn/problems/shortest-bridge/
+
 https://leetcode.cn/problems/partition-array-into-disjoint-intervals/
 
 https://leetcode.cn/problems/maximum-profit-in-job-scheduling/

booking-concert-tickets-in-groups/SegmentTree.ts

@@ -10,7 +10,6 @@ class SegmentTree<T> {
     ) {
         this.#root = new TreeNode<T>();
         this.#build(this.#root, start, end);
-
     }
     #build(node: TreeNode<T>, start: number, end: number) {
         if (start === end) {

partition-array-into-disjoint-intervals/index.ts

@@ -1,14 +1,14 @@
-export default function partitionDisjoint(nums: number[]): number {
-    const n = nums.length;
-    let leftMax = nums[0],
-        leftPos = 0,
-        curMax = nums[0];
-    for (let i = 1; i < n - 1; i++) {
-        curMax = Math.max(curMax, nums[i]);
-        if (nums[i] < leftMax) {
-            leftMax = curMax;
-            leftPos = i;
-        }
-    }
-    return leftPos + 1;
-}
+export default function partitionDisjoint(nums: number[]): number {
+    const n = nums.length;
+    let leftMax = nums[0],
+        leftPos = 0,
+        curMax = nums[0];
+    for (let i = 1; i < n - 1; i++) {
+        curMax = Math.max(curMax, nums[i]);
+        if (nums[i] < leftMax) {
+            leftMax = curMax;
+            leftPos = i;
+        }
+    }
+    return leftPos + 1;
+}

shortest-bridge/index.ts

@@ -0,0 +1,51 @@
+export default function shortestBridge(grid: number[][]): number {
+    const directions = [
+        [0, 1],
+        [1, 0],
+        [0, -1],
+        [-1, 0],
+    ];
+
+    let firstIsland: [number, number][] = [];
+    loop:
+    for (const [i, a] of grid.entries()) {
+        for (const [j, v] of a.entries()) {
+            if (v === 1) {
+                firstIsland.push([i, j]);
+
+                for (const [x, y] of firstIsland) {
+                    grid[x][y] = 2;
+                    for (const [q, w] of directions) {
+                        const [e, r] = [x + q, y + w];
+                        if (grid[e]?.[r] === 1) {
+                            firstIsland.push([e, r]);
+                            grid[e][r] = 2;
+                        }
+                    }
+                }
+                break loop;
+            }
+        }
+    }
+
+    let step = 0;
+    while (firstIsland.length) {
+        const temp: [number, number][] = [];
+        for (const [x, y] of firstIsland) {
+            grid[x][y] = 2;
+            for (const [q, w] of directions) {
+                const [e, r] = [x + q, y + w];
+                if (grid[e]?.[r] === 1) {
+                    return step;
+                }
+                if (grid[e]?.[r] === 0) {
+                    temp.push([e, r]);
+                    grid[e][r] = 2;
+                }
+            }
+        }
+        step++;
+        firstIsland = temp;
+    }
+    return -1;
+}