代码随想录day42（背包）

vector<vector<int>> dp(weight.size(), vector<int>(bagweight + 1, 0));
for (int j = weight[0]; j <= bagweight; j++) 
{
    dp[0][j] = value[0];
}
// weight数组的大小 就是物品个数
for(int i = 1; i < weight.size(); i++) 
{ // 遍历物品
    for(int j = 0; j <= bagweight; j++) 
    { // 遍历背包容量
        if (j < weight[i]) dp[i][j] = dp[i - 1][j];
        else dp[i][j] = max(dp[i - 1][j], dp[i - 1][j - weight[i]] + value[i]);

    }
}

vector<int> dp(bagWeight + 1, 0);
for(int i = 0; i < weight.size(); i++) { // 遍历物品
   for(int j = bagWeight; j >= weight[i]; j--) { // 遍历背包容量
      dp[j] = max(dp[j], dp[j - weight[i]] + value[i]);
   }
}

416分割等和子集

class Solution {
public:
    bool canPartition(vector<int>& nums) 
    {
        int sum=0;
        for(auto a:nums) sum+=a;
        if(sum%2!=0) return false;
        sum/=2;
        vector<int>dp(sum+1,0);
        for(int i=0;i<nums.size();i++)
        {
            for(int j=sum;j>=nums[i];j--)
            {
                dp[j]=max(dp[j],dp[j-nums[i]]+nums[i]);
            }
        }
        if(dp[sum]==sum) return true;
        return false;
    }
};