9.12|day 5|day 44 |完全背包| 518. 零钱兑换 II | 377. 组合总和 Ⅳ

● 完全背包

主要是看清01背包和完全背包的区别

//01背包
for(int i = 0;i<weight.size();i++){
for(int j = bagWeight;j>=weight[i];j--){dp[j] = Math.max(dp[j],dp[j-weight[i]]+value[i]);
}
}
//完全背包
for(int i = 0;i<weight.size();i++){for(int j =weight[i];j<=bagweight;j++){dp[j] = max(dp[j],dp[j-weight[i]]+value[i]);}
}

● 518. 零钱兑换 II

//完全背包经典题目
class Solution {public int change(int amount, int[] coins) {int[] dp = new int[amount+1];dp[0] = 1; for(int i = 0;i<coins.length;i++){for(int j =coins[i];j<=amount;j++){dp[j] += dp[j-coins[i]];//可以不断重复}}return dp[amount];}
}

● 377. 组合总和 Ⅳ

class Solution {public int combinationSum4(int[] nums, int target) {int[] dp = new int[target+1];dp[0] = 1;for(int i = 0;i<=target;i++){for(int j = 0;j<nums.length;j++){if(i>=nums[j]){dp[i] += dp[i-nums[j]];}}}return dp[target];}
}