Practice-Leetcode/EqualPartitionSum.cpp at master · adilhamid/Practice-Leetcode · GitHub

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class Solution {
public:
    bool canPartitionFail(vector<int>& nums) {

        sort(nums.begin(), nums.end());

        int forwardSum=0, backwardSum =0;

        forwardSum = nums[0];
        backwardSum = nums[nums.size()-1];

        int i=0, j = nums.size()-1;

        while(i<j){

            if(backwardSum == forwardSum ){
                if(i == j-1) return true;
                else{
                    forwardSum += nums[++i];
                    backwardSum += nums[--j];
                }
            }

            else if (forwardSum > backwardSum && i<j){
                    backwardSum += nums[--j];
            }

            else if (forwardSum < backwardSum && j>i){
                forwardSum += nums[++i];
            }

            else
             return false;
        }
        return false;

    }

     bool canPartitionDP(vector<int>& nums) {
         int sum = accumulate(nums.begin(), nums.end(),0);
         if(sum & 1) return false;
         int target = sum >> 1;
         vector<int> dp(target+1, 0);
         dp[0] = 1;
         for(int num : nums){
             for(int i = target; i>= num ; i--){
                 dp[i] = dp[i] || dp[i-num];
             }
         }
         return dp[target];
     }

       bool canPartition(vector<int>& nums) {
           int sum =0;
           bitset<((100*200) / 2) -1> bit(1);

           for(int num : nums){
               sum += num;
               bit |= bit << num;
           }

           return !(sum & 1) && bit[sum >> 1];
       }

};