我从输入中读到List[Int]。
我想将该列表的部分总和变为List[Long]。
val a: List[Int] = readLine().split(" ").map(_.toInt).toList
val sumList: List[Long] = a.scanLeft(0)(_.toLong + _.toLong).tail.toList
但是，我收到此错误：
Solution.scala:54: error: type mismatch;
found : Long
required: Int
val sumList: List[Long] = a.scanLeft(0)(_.toLong + _.toLong).tail.toList
^
Solution.scala:54: error: type mismatch;
found : List[Int]
required: List[Long]
val sumList: List[Long] = a.scanLeft(0)(_.toLong + _.toLong).tail.toList
^
知道我做错了什么吗？
答案 0 :(得分：2)
(function() {
'use strict';
var filesToCache = [
'.',
'index.html',
'pwa-stylesheets/css/styles-new.css'
];
var staticCacheName = 'cache-v3';
self.addEventListener( 'install', function(event) {
event.waitUntil(
caches.open(staticCacheName)
.then(function(cache) {
return cache.addAll(filesToCache);
}).then( function() {
self.skipWaiting();
})
);
});
self.addEventListener( 'fetch', function(event) {
var url = event.request.url;
if( url.indexOf( "http://localhost:8080" ) > -1
&& url.indexOf( "http://localhost:8080/api/" ) == -1
&& url.indexOf( "http://localhost:8080/pwa-" ) == -1 ) {
// event.request.url = "http://localhost:8080/"; // not allowed
event.respondWith(
caches.match(event.request).then( function( response ) {
if( response ) {
console.log( 'Found ', url, ' in cache' );
return response;
}
console.log( 'Network request for ', url );
return fetch( event.request ).then( function( response ) {
if( ! response.ok ) {
console.log( "Network request failed." );
return null;
}
return caches.open( staticCacheName ).then( function(cache) {
cache.put(event.request.url, response.clone());
return response;
});
});
})
);
}
});
self.addEventListener('activate', function(event) {
var cacheWhitelist = [staticCacheName];
event.waitUntil(
caches.keys().then(function(cacheNames) {
return Promise.all(
cacheNames.map(function(cacheName) {
if( cacheWhitelist.indexOf(cacheName) === -1 ) {
return caches.delete(cacheName);
}
})
);
})
);
});
})();
应为0。 ＆＃34;零值＆＃34;大多数功能操作似乎都是类型推断的基础。
答案 1 :(得分：2)
为什么不将最初的List设为List[Long]，因为您无论如何都要将Int转换为Long？
val a: List[Long] = readLine().split(" ").map(_.toLong).toList
val sumList: List[Long] = a.scanLeft(0L)(_ + _).tail.toList