{ "data": { "question": { "questionId": "3181", "questionFrontendId": "2940", "categoryTitle": "Algorithms", "boundTopicId": 2529067, "title": "Find Building Where Alice and Bob Can Meet", "titleSlug": "find-building-where-alice-and-bob-can-meet", "content": "
You are given a 0-indexed array heights
of positive integers, where heights[i]
represents the height of the ith
building.
If a person is in building i
, they can move to any other building j
if and only if i < j
and heights[i] < heights[j]
.
You are also given another array queries
where queries[i] = [ai, bi]
. On the ith
query, Alice is in building ai
while Bob is in building bi
.
Return an array ans
where ans[i]
is the index of the leftmost building where Alice and Bob can meet on the ith
query. If Alice and Bob cannot move to a common building on query i
, set ans[i]
to -1
.
\n
Example 1:
\n\n\nInput: heights = [6,4,8,5,2,7], queries = [[0,1],[0,3],[2,4],[3,4],[2,2]]\nOutput: [2,5,-1,5,2]\nExplanation: In the first query, Alice and Bob can move to building 2 since heights[0] < heights[2] and heights[1] < heights[2]. \nIn the second query, Alice and Bob can move to building 5 since heights[0] < heights[5] and heights[3] < heights[5]. \nIn the third query, Alice cannot meet Bob since Alice cannot move to any other building.\nIn the fourth query, Alice and Bob can move to building 5 since heights[3] < heights[5] and heights[4] < heights[5].\nIn the fifth query, Alice and Bob are already in the same building. \nFor ans[i] != -1, It can be shown that ans[i] is the leftmost building where Alice and Bob can meet.\nFor ans[i] == -1, It can be shown that there is no building where Alice and Bob can meet.\n\n\n
Example 2:
\n\n\nInput: heights = [5,3,8,2,6,1,4,6], queries = [[0,7],[3,5],[5,2],[3,0],[1,6]]\nOutput: [7,6,-1,4,6]\nExplanation: In the first query, Alice can directly move to Bob's building since heights[0] < heights[7].\nIn the second query, Alice and Bob can move to building 6 since heights[3] < heights[6] and heights[5] < heights[6].\nIn the third query, Alice cannot meet Bob since Bob cannot move to any other building.\nIn the fourth query, Alice and Bob can move to building 4 since heights[3] < heights[4] and heights[0] < heights[4].\nIn the fifth query, Alice can directly move to Bob's building since heights[1] < heights[6].\nFor ans[i] != -1, It can be shown that ans[i] is the leftmost building where Alice and Bob can meet.\nFor ans[i] == -1, It can be shown that there is no building where Alice and Bob can meet.\n\n\n\n
\n
Constraints:
\n\n1 <= heights.length <= 5 * 104
1 <= heights[i] <= 109
1 <= queries.length <= 5 * 104
queries[i] = [ai, bi]
0 <= ai, bi <= heights.length - 1
给你一个下标从 0 开始的正整数数组 heights
,其中 heights[i]
表示第 i
栋建筑的高度。
如果一个人在建筑 i
,且存在 i < j
的建筑 j
满足 heights[i] < heights[j]
,那么这个人可以移动到建筑 j
。
给你另外一个数组 queries
,其中 queries[i] = [ai, bi]
。第 i
个查询中,Alice 在建筑 ai
,Bob 在建筑 bi
。
请你能返回一个数组 ans
,其中 ans[i]
是第 i
个查询中,Alice 和 Bob 可以相遇的 最左边的建筑 。如果对于查询 i
,Alice 和 Bob 不能相遇,令 ans[i]
为 -1
。
\n\n
示例 1:
\n\n\n输入:heights = [6,4,8,5,2,7], queries = [[0,1],[0,3],[2,4],[3,4],[2,2]]\n输出:[2,5,-1,5,2]\n解释:第一个查询中,Alice 和 Bob 可以移动到建筑 2 ,因为 heights[0] < heights[2] 且 heights[1] < heights[2] 。\n第二个查询中,Alice 和 Bob 可以移动到建筑 5 ,因为 heights[0] < heights[5] 且 heights[3] < heights[5] 。\n第三个查询中,Alice 无法与 Bob 相遇,因为 Alice 不能移动到任何其他建筑。\n第四个查询中,Alice 和 Bob 可以移动到建筑 5 ,因为 heights[3] < heights[5] 且 heights[4] < heights[5] 。\n第五个查询中,Alice 和 Bob 已经在同一栋建筑中。\n对于 ans[i] != -1 ,ans[i] 是 Alice 和 Bob 可以相遇的建筑中最左边建筑的下标。\n对于 ans[i] == -1 ,不存在 Alice 和 Bob 可以相遇的建筑。\n\n\n
示例 2:
\n\n\n输入:heights = [5,3,8,2,6,1,4,6], queries = [[0,7],[3,5],[5,2],[3,0],[1,6]]\n输出:[7,6,-1,4,6]\n解释:第一个查询中,Alice 可以直接移动到 Bob 的建筑,因为 heights[0] < heights[7] 。\n第二个查询中,Alice 和 Bob 可以移动到建筑 6 ,因为 heights[3] < heights[6] 且 heights[5] < heights[6] 。\n第三个查询中,Alice 无法与 Bob 相遇,因为 Bob 不能移动到任何其他建筑。\n第四个查询中,Alice 和 Bob 可以移动到建筑 4 ,因为 heights[3] < heights[4] 且 heights[0] < heights[4] 。\n第五个查询中,Alice 可以直接移动到 Bob 的建筑,因为 heights[1] < heights[6] 。\n对于 ans[i] != -1 ,ans[i] 是 Alice 和 Bob 可以相遇的建筑中最左边建筑的下标。\n对于 ans[i] == -1 ,不存在 Alice 和 Bob 可以相遇的建筑。\n\n\n
\n\n
提示:
\n\n1 <= heights.length <= 5 * 104
1 <= heights[i] <= 109
1 <= queries.length <= 5 * 104
queries[i] = [ai, bi]
0 <= ai, bi <= heights.length - 1
[x, y]
, if x > y
, swap x
and y
. Now, we can assume that x <= y
.",
"For each query [x, y]
, if x == y
or heights[x] < heights[y]
, then the answer is y
since x ≤ y
.",
"Otherwise, we need to find the smallest index t
such that y < t
and heights[x] < heights[t]
. Note that heights[y] <= heights[x]
, so heights[x] < heights[t]
is a sufficient condition.",
"To find index t
for each query, sort the queries in descending order of y
. Iterate over the queries while maintaining a monotonic stack which we can binary search over to find index t
."
],
"solution": null,
"status": null,
"sampleTestCase": "[6,4,8,5,2,7]\n[[0,1],[0,3],[2,4],[3,4],[2,2]]",
"metaData": "{\n \"name\": \"leftmostBuildingQueries\",\n \"params\": [\n {\n \"name\": \"heights\",\n \"type\": \"integer[]\"\n },\n {\n \"type\": \"integer[][]\",\n \"name\": \"queries\"\n }\n ],\n \"return\": {\n \"type\": \"integer[]\"\n }\n}",
"judgerAvailable": true,
"judgeType": "large",
"mysqlSchemas": [],
"enableRunCode": true,
"envInfo": "{\"cpp\":[\"C++\",\"\\u7248\\u672c\\uff1a \\u7f16\\u8bd1\\u65f6\\uff0c\\u5c06\\u4f1a\\u91c7\\u7528 \\u4e3a\\u4e86\\u4f7f\\u7528\\u65b9\\u4fbf\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8\\u5bfc\\u5165\\u3002<\\/p>\"],\"java\":[\"Java\",\" \\u7248\\u672c\\uff1a \\u4e3a\\u4e86\\u65b9\\u4fbf\\u8d77\\u89c1\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u88ab\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n \\u5305\\u542b Pair \\u7c7b: https:\\/\\/docs.oracle.com\\/javase\\/8\\/javafx\\/api\\/javafx\\/util\\/Pair.html <\\/p>\"],\"python\":[\"Python\",\" \\u7248\\u672c\\uff1a \\u4e3a\\u4e86\\u65b9\\u4fbf\\u8d77\\u89c1\\uff0c\\u5927\\u90e8\\u5206\\u5e38\\u7528\\u5e93\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8 \\u5bfc\\u5165\\uff0c\\u5982\\uff1aarray<\\/a>, bisect<\\/a>, collections<\\/a>\\u3002\\u5982\\u679c\\u60a8\\u9700\\u8981\\u4f7f\\u7528\\u5176\\u4ed6\\u5e93\\u51fd\\u6570\\uff0c\\u8bf7\\u81ea\\u884c\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n \\u6ce8\\u610f Python 2.7 \\u5c06\\u57282020\\u5e74\\u540e\\u4e0d\\u518d\\u7ef4\\u62a4<\\/a>\\u3002 \\u5982\\u60f3\\u4f7f\\u7528\\u6700\\u65b0\\u7248\\u7684Python\\uff0c\\u8bf7\\u9009\\u62e9Python 3\\u3002<\\/p>\"],\"c\":[\"C\",\" \\u7248\\u672c\\uff1a \\u7f16\\u8bd1\\u65f6\\uff0c\\u5c06\\u4f1a\\u91c7\\u7528 \\u4e3a\\u4e86\\u4f7f\\u7528\\u65b9\\u4fbf\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n \\u5982\\u60f3\\u4f7f\\u7528\\u54c8\\u5e0c\\u8868\\u8fd0\\u7b97, \\u60a8\\u53ef\\u4ee5\\u4f7f\\u7528 uthash<\\/a>\\u3002 \\\"uthash.h\\\"\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5bfc\\u5165\\u3002\\u8bf7\\u770b\\u5982\\u4e0b\\u793a\\u4f8b:<\\/p>\\r\\n\\r\\n 1. \\u5f80\\u54c8\\u5e0c\\u8868\\u4e2d\\u6dfb\\u52a0\\u4e00\\u4e2a\\u5bf9\\u8c61\\uff1a<\\/b>\\r\\n 2. \\u5728\\u54c8\\u5e0c\\u8868\\u4e2d\\u67e5\\u627e\\u4e00\\u4e2a\\u5bf9\\u8c61\\uff1a<\\/b>\\r\\n 3. \\u4ece\\u54c8\\u5e0c\\u8868\\u4e2d\\u5220\\u9664\\u4e00\\u4e2a\\u5bf9\\u8c61\\uff1a<\\/b>\\r\\n C# 10<\\/a> \\u8fd0\\u884c\\u5728 .NET 6 \\u4e0a<\\/p>\"],\"javascript\":[\"JavaScript\",\" \\u7248\\u672c\\uff1a \\u60a8\\u7684\\u4ee3\\u7801\\u5728\\u6267\\u884c\\u65f6\\u5c06\\u5e26\\u4e0a lodash.js<\\/a> \\u5e93\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5305\\u542b\\u3002<\\/p>\\r\\n\\r\\n \\u5982\\u9700\\u4f7f\\u7528\\u961f\\u5217\\/\\u4f18\\u5148\\u961f\\u5217\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 datastructures-js\\/priority-queue@5.3.0<\\/a> \\u548c datastructures-js\\/queue@4.2.1<\\/a>\\u3002<\\/p>\"],\"ruby\":[\"Ruby\",\" \\u4f7f\\u7528 \\u4e00\\u4e9b\\u5e38\\u7528\\u7684\\u6570\\u636e\\u7ed3\\u6784\\u5df2\\u5728 Algorithms \\u6a21\\u5757\\u4e2d\\u63d0\\u4f9b\\uff1ahttps:\\/\\/www.rubydoc.info\\/github\\/kanwei\\/algorithms\\/Algorithms<\\/p>\"],\"swift\":[\"Swift\",\" \\u7248\\u672c\\uff1a \\u6211\\u4eec\\u901a\\u5e38\\u4fdd\\u8bc1\\u66f4\\u65b0\\u5230 Apple\\u653e\\u51fa\\u7684\\u6700\\u65b0\\u7248Swift<\\/a>\\u3002\\u5982\\u679c\\u60a8\\u53d1\\u73b0Swift\\u4e0d\\u662f\\u6700\\u65b0\\u7248\\u7684\\uff0c\\u8bf7\\u8054\\u7cfb\\u6211\\u4eec\\uff01\\u6211\\u4eec\\u5c06\\u5c3d\\u5feb\\u66f4\\u65b0\\u3002<\\/p>\"],\"golang\":[\"Go\",\" \\u7248\\u672c\\uff1a \\u652f\\u6301 https:\\/\\/godoc.org\\/github.com\\/emirpasic\\/gods@v1.18.1<\\/a> \\u7b2c\\u4e09\\u65b9\\u5e93\\u3002<\\/p>\"],\"python3\":[\"Python3\",\" \\u7248\\u672c\\uff1a \\u4e3a\\u4e86\\u65b9\\u4fbf\\u8d77\\u89c1\\uff0c\\u5927\\u90e8\\u5206\\u5e38\\u7528\\u5e93\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8 \\u5bfc\\u5165\\uff0c\\u5982array<\\/a>, bisect<\\/a>, collections<\\/a>\\u3002 \\u5982\\u679c\\u60a8\\u9700\\u8981\\u4f7f\\u7528\\u5176\\u4ed6\\u5e93\\u51fd\\u6570\\uff0c\\u8bf7\\u81ea\\u884c\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n \\u5982\\u9700\\u4f7f\\u7528 Map\\/TreeMap \\u6570\\u636e\\u7ed3\\u6784\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 sortedcontainers<\\/a> \\u5e93\\u3002<\\/p>\"],\"scala\":[\"Scala\",\" \\u7248\\u672c\\uff1a \\u7248\\u672c\\uff1a \\u6211\\u4eec\\u4f7f\\u7528\\u7684\\u662f JetBrains \\u63d0\\u4f9b\\u7684 experimental compiler\\u3002\\u5982\\u679c\\u60a8\\u8ba4\\u4e3a\\u60a8\\u9047\\u5230\\u4e86\\u7f16\\u8bd1\\u5668\\u76f8\\u5173\\u7684\\u95ee\\u9898\\uff0c\\u8bf7\\u5411\\u6211\\u4eec\\u53cd\\u9988<\\/p>\"],\"rust\":[\"Rust\",\" \\u7248\\u672c\\uff1a \\u652f\\u6301 crates.io \\u7684 rand<\\/a><\\/p>\"],\"php\":[\"PHP\",\" With bcmath module.<\\/p>\"],\"typescript\":[\"TypeScript\",\" TypeScript 5.1.6<\\/p>\\r\\n\\r\\n Compile Options: --alwaysStrict --strictBindCallApply --strictFunctionTypes --target ES2022<\\/p>\\r\\n\\r\\n lodash.js<\\/a> \\u5e93\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5305\\u542b\\u3002<\\/p>\\r\\n\\r\\n \\u5982\\u9700\\u4f7f\\u7528\\u961f\\u5217\\/\\u4f18\\u5148\\u961f\\u5217\\uff0c\\u60a8\\u53ef\\u4f7f\\u7528 datastructures-js\\/priority-queue@5.3.0<\\/a> \\u548c datastructures-js\\/queue@4.2.1<\\/a>\\u3002<\\/p>\"],\"racket\":[\"Racket\",\"clang 11<\\/code> \\u91c7\\u7528\\u6700\\u65b0C++ 20\\u6807\\u51c6\\u3002<\\/p>\\r\\n\\r\\n
-O2<\\/code>\\u7ea7\\u4f18\\u5316\\u3002AddressSanitizer<\\/a> \\u4e5f\\u88ab\\u5f00\\u542f\\u6765\\u68c0\\u6d4b
out-of-bounds<\\/code>\\u548c
use-after-free<\\/code>\\u9519\\u8bef\\u3002<\\/p>\\r\\n\\r\\n
OpenJDK 17<\\/code>\\u3002\\u53ef\\u4ee5\\u4f7f\\u7528Java 8\\u7684\\u7279\\u6027\\u4f8b\\u5982\\uff0clambda expressions \\u548c stream API\\u3002<\\/p>\\r\\n\\r\\n
Python 2.7.12<\\/code><\\/p>\\r\\n\\r\\n
GCC 8.2<\\/code>\\uff0c\\u91c7\\u7528GNU11\\u6807\\u51c6\\u3002<\\/p>\\r\\n\\r\\n
-O1<\\/code>\\u7ea7\\u4f18\\u5316\\u3002 AddressSanitizer<\\/a>\\u4e5f\\u88ab\\u5f00\\u542f\\u6765\\u68c0\\u6d4b
out-of-bounds<\\/code>\\u548c
use-after-free<\\/code>\\u9519\\u8bef\\u3002<\\/p>\\r\\n\\r\\n
\\r\\nstruct hash_entry {\\r\\n int id; \\/* we'll use this field as the key *\\/\\r\\n char name[10];\\r\\n UT_hash_handle hh; \\/* makes this structure hashable *\\/\\r\\n};\\r\\n\\r\\nstruct hash_entry *users = NULL;\\r\\n\\r\\nvoid add_user(struct hash_entry *s) {\\r\\n HASH_ADD_INT(users, id, s);\\r\\n}\\r\\n<\\/pre>\\r\\n<\\/p>\\r\\n\\r\\n
\\r\\nstruct hash_entry *find_user(int user_id) {\\r\\n struct hash_entry *s;\\r\\n HASH_FIND_INT(users, &user_id, s);\\r\\n return s;\\r\\n}\\r\\n<\\/pre>\\r\\n<\\/p>\\r\\n\\r\\n
\\r\\nvoid delete_user(struct hash_entry *user) {\\r\\n HASH_DEL(users, user); \\r\\n}\\r\\n<\\/pre>\\r\\n<\\/p>\"],\"csharp\":[\"C#\",\"
Node.js 16.13.2<\\/code><\\/p>\\r\\n\\r\\n
--harmony<\\/code> \\u6807\\u8bb0\\u6765\\u5f00\\u542f \\u65b0\\u7248ES6\\u7279\\u6027<\\/a>\\u3002<\\/p>\\r\\n\\r\\n
Ruby 3.1<\\/code>\\u6267\\u884c<\\/p>\\r\\n\\r\\n
Swift 5.5.2<\\/code><\\/p>\\r\\n\\r\\n
Go 1.21<\\/code><\\/p>\\r\\n\\r\\n
Python 3.10<\\/code><\\/p>\\r\\n\\r\\n
Scala 2.13<\\/code><\\/p>\"],\"kotlin\":[\"Kotlin\",\"
Kotlin 1.9.0<\\/code><\\/p>\\r\\n\\r\\n
rust 1.58.1<\\/code><\\/p>\\r\\n\\r\\n
PHP 8.1<\\/code>.<\\/p>\\r\\n\\r\\n