diff --git a/src/main/java/cn/whaifree/redo/redoAll/LeetCode1049.java b/src/main/java/cn/whaifree/redo/redoAll/LeetCode1049.java new file mode 100644 index 0000000..7ba99ec --- /dev/null +++ b/src/main/java/cn/whaifree/redo/redoAll/LeetCode1049.java @@ -0,0 +1,111 @@ +package cn.whaifree.redo.redoAll; + +import org.junit.Test; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/8/20 22:11 + * @注释 + */ +public class LeetCode1049 { + + @Test + public void test(){ + int[] arr = new int[]{2,7,4,1,8,1}; + int i = lastStoneWeightII1(arr); + System.out.println(i); + } + + /** + * + * dp[i][j] 表示从0-i中任意取，放入j获取的最大价值 + * + * half 为背包容量 + * + * 0 1 2 3 4 5 6 7 8 9 1011 + * index 0: 0 0 2 2 2 2 2 2 2 2 2 2 + * index 1: 0 0 2 2 2 2 2 2 2 2 2 9 + * index 2: 0 0 2 2 2 2 2 2 2 2 2 9 + * index 3: 0 0 2 2 2 2 2 2 2 2 2 9 + * index 4: 0 0 2 2 2 2 2 2 2 2 2 10 + * index 5: 0 0 2 2 2 2 2 2 2 2 2 10 + * + * + * + * @param stones + * @return + */ + public int lastStoneWeightII(int[] stones) { + int sum = 0; + for (int i = 0; i < stones.length; i++) { + sum += stones[i]; + } + + int half = sum / 2; + int[][] dp = new int[stones.length][half + 1]; + for (int i = stones[0]; i <= half; i++) { + dp[0][i] = stones[0]; + } + + + for (int i = 1; i < stones.length; i++) { + for (int j = 1; j <= half; j++) { + // 够放 + if (j >= stones[i]) { + // 放入 dp[i-1][j-nums[i]]+value[i] + // 不放 dp[i-1][j] + dp[i][j] = Math.max(dp[i - 1][j - stones[i]] + stones[i], dp[i - 1][j]); + } else { + dp[i][j] = dp[i - 1][j]; + } + } + } + + + return sum - dp[stones.length - 1][half] * 2; + } + + + public int lastStoneWeightII1(int[] stones) { + int sum = 0; + for (int i = 0; i < stones.length; i++) { + sum += stones[i]; + } + + int half = sum / 2; + int[] dp = new int[half + 1]; +// for (int i = stones[0]; i <= half; i++) { +// dp[i] = stones[0]; +// } + + for (int i = 0; i < stones.length; i++) { + for (int j = half; j >= stones[i]; j--) { + // 够放 + dp[j] = Math.max(dp[j], dp[j - stones[i]] + stones[i]); + } + } + /** + * 如果我们从前往后遍历： + * for (int j = stones[i]; j <= half; j++) { + * dp[j] = Math.max(dp[j], dp[j - stones[i]] + stones[i]); + * } + * 在这种情况下，当我们计算 dp[j] 时，dp[j - stones[i]] 可能已经被当前轮次的更新所影响。 + * 这意味着我们可能会错误地使用当前轮次中已经更新的值，而不是上一轮次的值。这会导致结果不正确。 + * + * 当我们计算 dp[j] 时，dp[j - stones[i]] 仍然是上一轮次的结果，因为我们在更新 dp[j] 之前还没有更新 + * dp[j - stones[i]]。这确保了我们使用的是正确的历史数据，从而得到正确的结果。 + */ + + /** + * [0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2] + * [0, 0, 2, 2, 2, 2, 2, 7, 7, 9, 9, 9] + * [0, 0, 2, 2, 4, 4, 6, 7, 7, 9, 9, 11] + * [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11] + * [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11] + * [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11] + */ + + return sum - dp[half] * 2; + } +} diff --git a/src/main/java/cn/whaifree/redo/redoAll/LeetCode209.java b/src/main/java/cn/whaifree/redo/redoAll/LeetCode209.java index 4bf2675..7158b8e 100644 --- a/src/main/java/cn/whaifree/redo/redoAll/LeetCode209.java +++ b/src/main/java/cn/whaifree/redo/redoAll/LeetCode209.java @@ -2,6 +2,8 @@ package cn.whaifree.redo.redoAll; import org.junit.Test; +import java.util.Arrays; + /** * @version 1.0 * @Author whai文海 @@ -14,7 +16,7 @@ public class LeetCode209 { public void test() { int[] nums = {1,2,3,4,5}; int target = 11; - int minSubArrayLen = new Solution().minSubArrayLen(target, nums); + int minSubArrayLen = new Solution1().minSubArrayLen(target, nums); System.out.println(minSubArrayLen); } @@ -39,4 +41,28 @@ public class LeetCode209 { return minLength == Integer.MAX_VALUE ? 0 : minLength; } } + + class Solution1{ + public int minSubArrayLen(int target, int[] nums) { + int[] preSum = new int[nums.length + 1]; + + for (int i = 1; i < preSum.length; i++) { + preSum[i] = preSum[i - 1] + nums[i - 1]; + } + + int minLen = Integer.MAX_VALUE; + for (int i = 0; i < preSum.length; i++) { + // preSum[right] = target + preSum[i] + int fill = target + preSum[i]; + int right = Arrays.binarySearch(preSum, fill); + if (right < 0) { + right = -right - 1; + } + if (right < preSum.length) { + minLen = Math.min(minLen, right - i); + } + } + return minLen; + } + } } diff --git a/src/main/java/cn/whaifree/redo/redoAll/LeetCode279.java b/src/main/java/cn/whaifree/redo/redoAll/LeetCode279.java new file mode 100644 index 0000000..276c5fd --- /dev/null +++ b/src/main/java/cn/whaifree/redo/redoAll/LeetCode279.java @@ -0,0 +1,70 @@ +package cn.whaifree.redo.redoAll; + +import org.junit.Test; + +/** + * @version 1.0 + * @Author whai文海 + * @Date 2024/8/20 23:30 + * @注释 + */ +public class LeetCode279 { + + @Test + public void test() { + int n = 13; + int i = new Solution().numSquares(n); + System.out.println(i); + } + + class Solution { + /** + * dp[j] 表示容量为j的背包需要几个完全平方数，可以填满 + * + * @param n + * @return + */ + public int numSquares(int n) { + int pakage = n + 1; + int[] dp = new int[pakage]; + for (int i = 1; i <= n; i++) { + dp[i] = i; + } + + for (int i = 2; i <= n; i++) { + for (int j = i * i; j <= n; j++) { + dp[j] = Math.min(dp[j], dp[j - i * i] + 1); + } + } + + return dp[n]; + } + } + + class Solution1 { + /** + * dp[j] 表示容量为j的背包需要几个完全平方数，可以填满 + * + * @param n + * @return + */ + public int numSquares(int n) { + int pakage = n + 1; + int x = (int) Math.floor(Math.sqrt(n)); + int[][] dp = new int[x + 1][pakage]; + for (int i = 0; i <= n; i++) { + dp[1][i] = Integer.MAX_VALUE; + } + + for (int i = 1; i <= x; i++) { + for (int j = i; j <= n; j++) { + dp[i][j] = dp[i - 1][j]; + if (j >= i * i) + dp[i][j] = Math.min(dp[i][j - i * i] + 1, dp[i][j]); + } + } + + return dp[x][n]; + } + } +} diff --git a/src/main/java/cn/whaifree/redo/redoAll/LeetCode713.java b/src/main/java/cn/whaifree/redo/redoAll/LeetCode713.java index 57c3afd..5c49749 100644 --- a/src/main/java/cn/whaifree/redo/redoAll/LeetCode713.java +++ b/src/main/java/cn/whaifree/redo/redoAll/LeetCode713.java @@ -51,7 +51,9 @@ public class LeetCode713 { } right++; res += right - left; + } + return res; } }