function maxSubSum(arr,left,right){ //console.log(right); var leftMaxSum = rightMaxSum = 0; //将这俩行代码放这里就会出错，是因为什么？ // var leftMaxBorderSum = rightMaxBorderSum = 0; // var lefttemp = righttemp = 0; if(left == right){ if(arr[left] > 0){ return arr[left]; }else{ return 0; } } var center = Math.floor((left + right)/2); var leftMaxSum = maxSubSum(arr,left,center); var rightMaxSum = maxSubSum(arr,center+1,right); //console.log(leftMaxBorderSum,rightMaxBorderSum); //把代码放这里就不会出错，是因为什么？ var leftMaxBorderSum = rightMaxBorderSum = 0; var lefttemp = righttemp = 0; for(var i=center; i>=left; i--){ lefttemp += arr[i]; if(lefttemp >= leftMaxBorderSum){ leftMaxBorderSum = lefttemp; } } for(var j=center+1; j<=right; j++){ righttemp += arr[j]; //console.log(j); if(righttemp >= rightMaxBorderSum){ rightMaxBorderSum = righttemp; } } console.log('['+left+','+right+']'); console.log(center+','+leftMaxSum+','+rightMaxSum+','+ (leftMaxBorderSum + rightMaxBorderSum)); return Math.max(leftMaxSum,rightMaxSum,(leftMaxBorderSum + rightMaxBorderSum)); } var arr = [4,-3,5,-2,-1,2,6,-2]; console.log(maxSubSum(arr,0,7));