java">classSolution{publicintlargestSumAfterKNegations(int[] nums,int k){// 将基本类型的int数组转换成IntStream,以便进行流操作。nums =Arrays.stream(nums)// 将IntStream中的int元素转换(装箱)为Integer对象,这是必须的因为后面的sorted方法需要对象来进行比较。.boxed()// 对流中的元素进行排序。使用自定义的比较器,该比较器基于元素的绝对值进行降序排序。// o1和o2是比较的两个元素,Math.abs(o2) - Math.abs(o1)计算结果如果为正数,则o2排在o1前面,实现降序。.sorted((o1, o2)->Math.abs(o2)-Math.abs(o1))// 将流中的Integer对象转换回基本类型int,以便可以将流转换回数组。.mapToInt(Integer::intValue)// 将流中的元素收集到一个新的int数组中。.toArray();for(int i =0; i < nums.length && k >0; i++){if(nums[i]<0){nums[i]= nums[i]*-1;k--;}}if(k ==0|| k %2==0){returnArrays.stream(nums).sum();}else{nums[nums.length -1]= nums[nums.length -1]*-1;returnArrays.stream(nums).sum();}}}
力扣 134. 加油站
java">classSolution{publicintcanCompleteCircuit(int[] gas,int[] cost){int[] res =newint[gas.length];for(int i =0; i < gas.length; i++){res[i]= gas[i]- cost[i];}if(Arrays.stream(res).sum()<0){return-1;}else{int idx =0;int sum =0;while(idx < res.length){int i;for(i = idx; i < res.length; i++){sum += res[i];if(sum <0){sum =0;idx = i +1;break;}}if(i == res.length)return idx;}}return-1;}}
力扣 135. 分发糖果
java">classSolution{publicintcandy(int[] ratings){int[]LToR=newint[ratings.length];LToR[0]=1;for(int i =1; i < ratings.length; i++){if(ratings[i]> ratings[i -1]){LToR[i]=LToR[i -1]+1;}else{LToR[i]=1;}}int[]RToL=newint[ratings.length];RToL[ratings.length -1]=1;for(int i = ratings.length -2; i >=0; i--){if(ratings[i]> ratings[i +1]){RToL[i]=RToL[i +1]+1;}else{RToL[i]=1;}}int[] result =newint[ratings.length];for(int i =0; i < ratings.length; i++){result[i]=Math.max(LToR[i],RToL[i]);}int sum =Arrays.stream(result).sum();return sum;}}
前端地址 http://192.168.0.125:4021
请求后端地址的时候报
from origin http://192.168.0.125:4021 has been blocked by CORS policy:
Request header field userid is not allowed by Access-Control-Allow-Headers in preflight response.
大概意思是请求 header里有个…