题解 | #目标和#

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param nums int整型一维数组 
     * @param target int整型 
     * @return int整型
     */
    int res=0;
    public int findTargetSumWays (int[] nums, int target) {
        // write code here
        if(nums.length==0)return 0;
        int count=0;
        help(nums,target,0,count);
        return  res;
    }
    public void help(int[]nums,int target,int index,int count){
        if(index==nums.length-1){
            if(count+nums[index]==target){
             res++;
            }if(count-nums[index]==target){
                res++;
            }
                return;
            
        }
              if(index>nums.length)return;
                count=count+nums[index];//+号
                help(nums,target,index+1,count);
                count=count-2*nums[index];//-号
                help(nums,target,index+1,count);
        }
    
}