a week7

wzx140 · wzx140 · commit 27b2b704b390 · 2019-11-05T11:55:49.000+08:00
diff --git a/AlgorithmBasis/week7/q1.cpp b/AlgorithmBasis/week7/q1.cpp
@@ -0,0 +1,95 @@
+﻿#include <iostream>
+#include <vector>
+#include <string>
+
+using std::vector;
+using std::cin;
+using std::cout;
+using std::endl;
+using std::string;
+
+// 1：Shredding Company
+// 将一串数字分割，使得分割后的数字和最接近 target(不大于)
+// 1. 如果数字正好等于target，则不会剪切
+// 2. 如果多种最接近target的方案，则输出 rejected
+// 3. 如果数字和大于target，则输出 error
+// 4. 否则输出sum和方案
+
+int minDifference = 2147483647;	// 与target的最小差
+int target = -1;
+int state = -1;					// 状态 0->存在解决方案 1->重复 -1->无解决方案
+vector<int> tempSolution;		// 临时存储解决方案
+vector<int> solution;			// minDifference对应的解决方案
+
+// divisor最多比num的长度多1
+bool divisorInNum(int num, int divisor) {
+	if (num / divisor != 0) {
+		return true;
+	}
+
+	if (num / divisor == 0 && num / (divisor / 10) != 0) {
+		return true;
+	}
+
+	return false;
+}
+
+void dfs(int num, int difference) {
+
+	// 最优化剪枝
+	if (difference - num > minDifference) {
+		return;
+	}
+	// 可行性剪枝
+	if (difference < 0 || (difference == 0 && num != 0)) {
+		return;
+	}
+	if (num == 0) {
+		if (difference < minDifference) {
+			state = 0;
+			// 保存符合要求的解决方案
+			minDifference = difference;
+			solution = tempSolution;
+		} else if (difference == minDifference) {
+			state = 1;
+		}
+		return;
+	}
+
+	int divisor = 10;
+	while (num != 0 && divisorInNum(num, divisor)) {
+		int splitor = num % divisor;
+		tempSolution.push_back(splitor);
+		dfs(num / divisor, difference - splitor);
+		// 回溯
+		tempSolution.pop_back();
+		divisor *= 10;
+	}
+}
+
+int main(int argc, char *argv[]) {
+	int num = -1;
+	while (cin >> target >> num && target != 0 && num != 0) {
+		minDifference = 2147483647;
+		state = -1;
+		if (num == target) {
+			cout << num << ' ' << num << endl;
+		} else {
+			dfs(num, target);
+			if (state == 0) {
+				cout << target - minDifference;
+				// 倒序遍历
+				for (int i = solution.size() - 1; i >= 0; i--) {
+					cout << " " << solution[i];
+				}
+				cout << endl;
+			} else if (state == -1) {
+				cout << "error" << endl;
+			} else if (state == 1) {
+				cout << "rejected" << endl;
+			}
+		}
+	}
+
+	return 0;
+}
