1049. 最后一块石头的重量 II - 力扣（LeetCode）

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

        int[] dp = new int[weight+1];
        
        for(int i=0;i<=weight;i++){
            if(i>=stones[0]){
                dp[i] = stones[0];
            }
        }
        
        for(int i=1;i<stones.length;i++){
            for (int j=weight;j>=stones[i];j--){
                dp[j] = Math.max(dp[j],dp[j-stones[i]] +stones[i]);
            }
        }
        
        return sum - 2*dp[weight];
    }
}

494. 目标和 - 力扣（LeetCode）

class Solution {
    public int findTargetSumWays(int[] nums, int target) {
        int sum = 0;
        for (int i = 0; i < nums.length; i++) {
            sum += nums[i];
        }

        if (sum < Math.abs(target) || (sum + target) % 2 != 0) {
            return 0;
        }

        int weight = (sum + target) / 2;
        int[][] dp = new int[nums.length][weight+1];

        for(int i=0;i<=weight;i++){
            if(nums[0] == i){
                dp[0][i] = 1;
            }
        }

        int zeroNum = 0;
        for(int i=0;i<nums.length;i++){
            if(nums[i] == 0){
                zeroNum++;
            }

            dp[i][0] = (int)Math.pow(2,zeroNum);
        }
        
        for (int i=1;i<nums.length;i++){
            for(int j=1;j<=weight;j++){
                if(j>=nums[i]){
                    dp[i][j] = dp[i-1][j] + dp[i-1][j-nums[i]];
                }else{
                    dp[i][j] = dp[i-1][j];
                }
            }
        }
        
        return dp[nums.length-1][weight];
    }
}

474. 一和零 - 力扣（LeetCode）

class Solution {
    public int findMaxForm(String[] strs, int m, int n) {
        int[][] dp = new int[m + 1][n + 1];

        for (int i = 0; i < strs.length; i++) {
            int[] zeroOneNumCount = getZeroOneNumCount(strs[i]);
            int zeroNum = zeroOneNumCount[0];
            int oneNum = zeroOneNumCount[1];

            for (int j = m; j >= zeroNum; j--) {
                for (int k = n; k >= oneNum; k--) {
                    dp[j][k] = Math.max(dp[j][k], dp[j - zeroNum][k - oneNum] + 1);
                }
            }
        }

        return dp[m][n];
    }

    private int[] getZeroOneNumCount(String str) {
        int[] zeroOneNumCount = new int[2];

        char[] chars = str.toCharArray();
        for (int i = 0; i < chars.length; i++) {
            if (chars[i] == '0') {
                zeroOneNumCount[0]++;
            } else {
                zeroOneNumCount[1]++;
            }
        }

        return zeroOneNumCount;
    }
}