为什么这个（部分）MergeSort实现吹的堆栈？
我正在经历制作自己的MergeSort实现的步骤。 它是recursion的，有一个基本的情况。 我没有做的唯一的事情就是长度为％2！= 0的数组不完美。所以你必须插入2 ^ n长度的数组。 我可以稍后解决。 但是，当我插入一个长度为4的数组时，我得到一个堆栈溢出。 为什么？
代码如下：
function mergeSort(arr){ // step 0 - establish the variables let newArr = [], len = arr.length; // step 1 - divide the problem into smaller parts until no longer possible if(len <= 1){ return arr; } if (len === 2){ newArr = (arr[0] < arr[1]) ? arr : arr.reverse(); } else { let arr1 = arr.slice(0, len/2), arr2 = arr.slice(len/2, len); // step 2 - conquer each small problem arr1 = mergeSort(arr1); arr2 = mergeSort(arr2); // step 3 - bring them back together while(arr1.length > 0 || arr2.length > 0){ if (!arr1[0]){ newArr = [...newArr, ...arr2]; break; } if (!arr2[0]) { newArr = [...newArr, ...arr1]; break; } arr1[0] < arr2[0] ? newArr.push(arr1.shift) : newArr.push(arr2.shift); } } // step 4 - return the new array return newArr; } 当我在Node中运行mergeSort([4,3,2,1]) ，
> mergeSort([1,2,3,4]) <--- Last few GCs ---> 14198 ms: Mark-sweep 1074.0 (1080.2) -> 862.8 (872.4) MB, 8.8 / 0.0 ms (+ 515.6 ms in 2 steps since start of marking, biggest step 400.2 ms) [GC interrupt] [GC in old space requested]. 14859 ms: Mark-sweep 862.8 (872.4) -> 361.0 (370.6) MB, 185.2 / 0.0 ms [allocation failure] [GC in old space requested]. 15922 ms: Mark-sweep 895.8 (905.4) -> 539.3 (548.8) MB, 201.6 / 0.0 ms [allocation failure] [GC in old space requested]. <--- JS stacktrace ---> ==== JS stack trace ========================================= Security context: 0x186ecb3cfb51 <JS Object> 2: mergeSort [/Users/waleo/Projects/algorithms/mergesort.js:~1] [pc=0x8c4e2bbcf4f] (this=0x186ecb3e6ee9 <JS Global Object>,arr=0x3b3bf2463f21 <JS Array[4]>) 3: /* anonymous */ [repl:1] [pc=0x8c4e2bba890] (this=0x186ecb3e6ee9 <JS Global Object>) 7: /* anonymous */(aka /* anonymous */) [vm.js:22] [pc=0x8c4e2b9eb48] (this=0x186ecb304381 <undefined>) 8: sigintHandlersWrap(aka sigint... FATAL ERROR: invalid array length Allocation failed - JavaScript heap out of memory 1: node::Abort() [/usr/local/bin/node] 2: node::FatalException(v8::Isolate*, v8::Local<v8::Value>, v8::Local<v8::Message>) [/usr/local/bin/node] 3: v8::internal::V8::FatalProcessOutOfMemory(char const*, bool) [/usr/local/bin/node] 4: v8::internal::Heap::AllocateUninitializedFixedArray(int) [/usr/local/bin/node] 5: v8::internal::Factory::NewUninitializedFixedArray(int) [/usr/local/bin/node] 6: v8::internal::(anonymous namespace)::FastElementsAccessor<v8::internal::(anonymous namespace)::FastPackedObjectElementsAccessor, v8::internal::(anonymous namespace)::ElementsKindTraits<(v8::internal::ElementsKind)2> >::AddArguments(v8::internal::Handle<v8::internal::JSArray>, v8::internal::Handle<v8::internal::FixedArrayBase>, v8::internal::Arguments*, unsigned int, v8::internal::(anonymous namespace)::Where) [/usr/local/bin/node] 7: v8::internal::(anonymous namespace)::DoArrayPush(v8::internal::Isolate*, v8::internal::(anonymous namespace)::BuiltinArguments<(v8::internal::BuiltinExtraArguments)0>) [/usr/local/bin/node] 8: v8::internal::Runtime_ArrayPush(int, v8::internal::Object**, v8::internal::Isolate*) [/usr/local/bin/node] 9: 0x8c4e2a079a7 [1] 65429 abort node
这里有什么问题？ 我怎样才能解决这个问题，以便recursionmergeSort不会吹我的堆栈？
你不用()调用.shift – 使它变成.shift() 。