代码随想录一刷day43

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一、力扣1049.最后一块石头的重量II

class Solution {
    public int lastStoneWeightII(int[] stones) {
        int sum = 0;
        for(int i : stones){
            sum += i;
        }
        int target = sum / 2;
        int[] dp = new int[target + 1];
        for(int i = 0; i < stones.length; i ++){
            for(int j = target; j >= stones[i]; j --){
                dp[j] = Math.max(dp[j] , dp[j - stones[i]] + stones[i]);
            }
        }
        return sum - 2 * dp[target];
    }
}

二、力扣494.目标和

class Solution {
    public int findTargetSumWays(int[] nums, int target) {
        int sum = 0;
        for(int i : nums){
            sum += i;
        }
        if(target < 0 && sum < -target)return 0;
        if((target + sum)%2 != 0)return 0;
        int size = (target + sum)/2;
        if(size < 0)size = -size;
        int[] dq = new int[size + 1];
        dq[0] = 1;
        for(int i = 0; i < nums.length; i ++){
            for(int j = size; j >= nums[i]; j --){
                dq[j] += dq[j - nums[i]];
            }
        }
        return dq[size];
    }
}

三、力扣474. 一和零

class Solution {
    public int findMaxForm(String[] strs, int m, int n) {
        int[][] dp = new int[m+1][n+1];
        for(String str: strs){
            int zeroNum = 0;
            int oneNum = 0;
            for(char ch : str.toCharArray()){
                if(ch == '0'){
                    zeroNum ++;
                }else{
                    oneNum ++;
                }
            }
            for(int i = m; i >= zeroNum; i --){
                for(int j = n; j >= oneNum; j --){
                    dp[i][j] = Math.max(dp[i][j], dp[i - zeroNum][j - oneNum] + 1);
                }
            }
        }
        return dp[m][n];
    }   
}