This commit is contained in:
krahets
2023-08-04 05:24:49 +08:00
parent c4046ca688
commit fafdebb75c
27 changed files with 972 additions and 536 deletions
+11 -11
View File
@@ -338,14 +338,14 @@ comments: true
return;
}
// 尝试
vectorPushback(path, root);
vectorPushback(path, root, sizeof(TreeNode));
if (root->val == 7) {
// 记录解
vector *newPath = newVector();
for (int i = 0; i < path->size; i++) {
vectorPushback(newPath, path->data[i]);
vectorPushback(newPath, path->data[i], sizeof(int));
}
vectorPushback(res, newPath);
vectorPushback(res, newPath, sizeof(vector));
}
preOrder(root->left, path, res);
@@ -635,14 +635,14 @@ comments: true
return;
}
// 尝试
vectorPushback(path, root);
vectorPushback(path, root, sizeof(TreeNode));
if (root->val == 7) {
// 记录解
vector *newPath = newVector();
for (int i = 0; i < path->size; i++) {
vectorPushback(newPath, path->data[i]);
vectorPushback(newPath, path->data[i], sizeof(int));
}
vectorPushback(res, newPath);
vectorPushback(res, newPath, sizeof(vector));
res->depth++;
}
@@ -1334,9 +1334,9 @@ comments: true
void recordSolution(vector *state, vector *res) {
vector *newPath = newVector();
for (int i = 0; i < state->size; i++) {
vectorPushback(newPath, state->data[i]);
vectorPushback(newPath, state->data[i], sizeof(int));
}
vectorPushback(res, newPath);
vectorPushback(res, newPath, sizeof(vector));
}
/* 判断在当前状态下,该选择是否合法 */
@@ -1346,7 +1346,7 @@ comments: true
/* 更新状态 */
void makeChoice(vector *state, TreeNode *choice) {
vectorPushback(state, choice);
vectorPushback(state, choice, sizeof(TreeNode));
}
/* 恢复状态 */
@@ -1371,8 +1371,8 @@ comments: true
makeChoice(state, choice);
// 进行下一轮选择
vector *nextChoices = newVector();
vectorPushback(nextChoices, choice->left);
vectorPushback(nextChoices, choice->right);
vectorPushback(nextChoices, choice->left, sizeof(TreeNode));
vectorPushback(nextChoices, choice->right, sizeof(TreeNode));
backtrack(state, nextChoices, res);
// 回退:撤销选择,恢复到之前的状态
undoChoice(state, choice);
+2 -2
View File
@@ -13,9 +13,9 @@ icon: material/map-marker-path
!!! abstract
我们如同迷宫中的探索者,在寻找出口的道路上可能会遇到困难。
我们如同迷宫中的探索者,在前进的道路上可能会遇到困难。
回溯的力量让我们能够重新开始,最终找到正确的道路
回溯的力量让我们能够重新开始,不断尝试,最终找到通往光明的出口
## 本章内容
+4 -4
View File
@@ -275,9 +275,9 @@ comments: true
if (state->size == choices->size) {
vector *newState = newVector();
for (int i = 0; i < state->size; i++) {
vectorPushback(newState, state->data[i]);
vectorPushback(newState, state->data[i], sizeof(int));
}
vectorPushback(res, newState);
vectorPushback(res, newState, sizeof(vector));
return;
}
// 遍历所有选择
@@ -289,7 +289,7 @@ comments: true
if (!select) {
// 尝试:做出选择,更新状态
*((bool *)selected->data[i]) = true;
vectorPushback(state, choice);
vectorPushback(state, choice, sizeof(int));
// 进行下一轮选择
backtrack(state, choices, selected, res);
// 回退:撤销选择,恢复到之前的状态
@@ -306,7 +306,7 @@ comments: true
int select[3] = {false, false, false};
vector *bSelected = newVector();
for (int i = 0; i < nums->size; i++) {
vectorPushback(bSelected, &select[i]);
vectorPushback(bSelected, &select[i], sizeof(int));
}
vector *res = newVector();
+229 -27
View File
@@ -166,17 +166,77 @@ comments: true
=== "JS"
```javascript title="subset_sum_i_naive.js"
[class]{}-[func]{backtrack}
/* 回溯算法:子集和 I */
function backtrack(state, target, total, choices, res) {
// 子集和等于 target 时,记录解
if (total === target) {
res.push([...state]);
return;
}
// 遍历所有选择
for (let i = 0; i < choices.length; i++) {
// 剪枝:若子集和超过 target ,则跳过该选择
if (total + choices[i] > target) {
continue;
}
// 尝试:做出选择,更新元素和 total
state.push(choices[i]);
// 进行下一轮选择
backtrack(state, target, total + choices[i], choices, res);
// 回退:撤销选择,恢复到之前的状态
state.pop();
}
}
[class]{}-[func]{subsetSumINaive}
/* 求解子集和 I(包含重复子集) */
function subsetSumINaive(nums, target) {
const state = []; // 状态(子集)
const total = 0; // 子集和
const res = []; // 结果列表(子集列表)
backtrack(state, target, total, nums, res);
return res;
}
```
=== "TS"
```typescript title="subset_sum_i_naive.ts"
[class]{}-[func]{backtrack}
/* 回溯算法:子集和 I */
function backtrack(
state: number[],
target: number,
total: number,
choices: number[],
res: number[][]
): void {
// 子集和等于 target 时,记录解
if (total === target) {
res.push([...state]);
return;
}
// 遍历所有选择
for (let i = 0; i < choices.length; i++) {
// 剪枝:若子集和超过 target ,则跳过该选择
if (total + choices[i] > target) {
continue;
}
// 尝试:做出选择,更新元素和 total
state.push(choices[i]);
// 进行下一轮选择
backtrack(state, target, total + choices[i], choices, res);
// 回退:撤销选择,恢复到之前的状态
state.pop();
}
}
[class]{}-[func]{subsetSumINaive}
/* 求解子集和 I(包含重复子集) */
function subsetSumINaive(nums: number[], target: number): number[][] {
const state = []; // 状态(子集)
const total = 0; // 子集和
const res = []; // 结果列表(子集列表)
backtrack(state, target, total, nums, res);
return res;
}
```
=== "C"
@@ -188,9 +248,9 @@ comments: true
if (total == target) {
vector *tmpVector = newVector();
for (int i = 0; i < state->size; i++) {
vectorPushback(tmpVector, state->data[i]);
vectorPushback(tmpVector, state->data[i], sizeof(int));
}
vectorPushback(res, tmpVector);
vectorPushback(res, tmpVector, sizeof(vector));
return;
}
// 遍历所有选择
@@ -200,7 +260,7 @@ comments: true
continue;
}
// 尝试:做出选择,更新元素和 total
vectorPushback(state, choices->data[i]);
vectorPushback(state, choices->data[i], sizeof(int));
// 进行下一轮选择
backtrack(state, target, total + *(int *)(choices->data[i]), choices, res);
// 回退:撤销选择,恢复到之前的状态
@@ -533,17 +593,83 @@ comments: true
=== "JS"
```javascript title="subset_sum_i.js"
[class]{}-[func]{backtrack}
/* 回溯算法:子集和 I */
function backtrack(state, target, choices, start, res) {
// 子集和等于 target 时,记录解
if (target === 0) {
res.push([...state]);
return;
}
// 遍历所有选择
// 剪枝二:从 start 开始遍历,避免生成重复子集
for (let i = start; i < choices.length; i++) {
// 剪枝一:若子集和超过 target ,则直接结束循环
// 这是因为数组已排序,后边元素更大,子集和一定超过 target
if (target - choices[i] < 0) {
break;
}
// 尝试:做出选择,更新 target, start
state.push(choices[i]);
// 进行下一轮选择
backtrack(state, target - choices[i], choices, i, res);
// 回退:撤销选择,恢复到之前的状态
state.pop();
}
}
[class]{}-[func]{subsetSumI}
/* 求解子集和 I */
function subsetSumI(nums, target) {
const state = []; // 状态(子集)
nums.sort(); // 对 nums 进行排序
const start = 0; // 遍历起始点
const res = []; // 结果列表(子集列表)
backtrack(state, target, nums, start, res);
return res;
}
```
=== "TS"
```typescript title="subset_sum_i.ts"
[class]{}-[func]{backtrack}
/* 回溯算法:子集和 I */
function backtrack(
state: number[],
target: number,
choices: number[],
start: number,
res: number[][]
): void {
// 子集和等于 target 时,记录解
if (target === 0) {
res.push([...state]);
return;
}
// 遍历所有选择
// 剪枝二:从 start 开始遍历,避免生成重复子集
for (let i = start; i < choices.length; i++) {
// 剪枝一:若子集和超过 target ,则直接结束循环
// 这是因为数组已排序,后边元素更大,子集和一定超过 target
if (target - choices[i] < 0) {
break;
}
// 尝试:做出选择,更新 target, start
state.push(choices[i]);
// 进行下一轮选择
backtrack(state, target - choices[i], choices, i, res);
// 回退:撤销选择,恢复到之前的状态
state.pop();
}
}
[class]{}-[func]{subsetSumI}
/* 求解子集和 I */
function subsetSumI(nums: number[], target: number): number[][] {
const state = []; // 状态(子集)
nums.sort(); // 对 nums 进行排序
const start = 0; // 遍历起始点
const res = []; // 结果列表(子集列表)
backtrack(state, target, nums, start, res);
return res;
}
```
=== "C"
@@ -555,9 +681,9 @@ comments: true
if (target == 0) {
vector *tmpVector = newVector();
for (int i = 0; i < state->size; i++) {
vectorPushback(tmpVector, state->data[i]);
vectorPushback(tmpVector, state->data[i], sizeof(int));
}
vectorPushback(res, tmpVector);
vectorPushback(res, tmpVector, sizeof(vector));
return;
}
// 遍历所有选择
@@ -565,10 +691,10 @@ comments: true
for (int i = start; i < choices->size; i++) {
// 剪枝:若子集和超过 target ,则跳过该选择
if (target - *(int *)(choices->data[i]) < 0) {
continue;
break;
}
// 尝试:做出选择,更新 target, start
vectorPushback(state, choices->data[i]);
vectorPushback(state, choices->data[i], sizeof(int));
// 进行下一轮选择
backtrack(state, target - *(int *)(choices->data[i]), choices, i, res);
// 回退:撤销选择,恢复到之前的状态
@@ -578,10 +704,10 @@ comments: true
/* 求解子集和 I */
vector *subsetSumI(vector *nums, int target) {
vector *state = newVector(); // 状态(子集)
qsort(nums->data[0], nums->size, sizeof(int), comp); // 对 nums 进行排序
int start = 0; // 子集和
vector *res = newVector(); // 结果列表(子集列表)
vector *state = newVector(); // 状态(子集)
qsort(nums->data, nums->size, sizeof(int *), comp); // 对 nums 进行排序
int start = 0; // 子集和
vector *res = newVector(); // 结果列表(子集列表)
backtrack(state, target, nums, start, res);
return res;
}
@@ -917,17 +1043,93 @@ comments: true
=== "JS"
```javascript title="subset_sum_ii.js"
[class]{}-[func]{backtrack}
/* 回溯算法:子集和 II */
function backtrack(state, target, choices, start, res) {
// 子集和等于 target 时,记录解
if (target === 0) {
res.push([...state]);
return;
}
// 遍历所有选择
// 剪枝二:从 start 开始遍历,避免生成重复子集
// 剪枝三:从 start 开始遍历,避免重复选择同一元素
for (let i = start; i < choices.length; i++) {
// 剪枝一:若子集和超过 target ,则直接结束循环
// 这是因为数组已排序,后边元素更大,子集和一定超过 target
if (target - choices[i] < 0) {
break;
}
// 剪枝四:如果该元素与左边元素相等,说明该搜索分支重复,直接跳过
if (i > start && choices[i] === choices[i - 1]) {
continue;
}
// 尝试:做出选择,更新 target, start
state.push(choices[i]);
// 进行下一轮选择
backtrack(state, target - choices[i], choices, i + 1, res);
// 回退:撤销选择,恢复到之前的状态
state.pop();
}
}
[class]{}-[func]{subsetSumII}
/* 求解子集和 II */
function subsetSumII(nums, target) {
const state = []; // 状态(子集)
nums.sort(); // 对 nums 进行排序
const start = 0; // 遍历起始点
const res = []; // 结果列表(子集列表)
backtrack(state, target, nums, start, res);
return res;
}
```
=== "TS"
```typescript title="subset_sum_ii.ts"
[class]{}-[func]{backtrack}
/* 回溯算法:子集和 II */
function backtrack(
state: number[],
target: number,
choices: number[],
start: number,
res: number[][]
): void {
// 子集和等于 target 时,记录解
if (target === 0) {
res.push([...state]);
return;
}
// 遍历所有选择
// 剪枝二:从 start 开始遍历,避免生成重复子集
// 剪枝三:从 start 开始遍历,避免重复选择同一元素
for (let i = start; i < choices.length; i++) {
// 剪枝一:若子集和超过 target ,则直接结束循环
// 这是因为数组已排序,后边元素更大,子集和一定超过 target
if (target - choices[i] < 0) {
break;
}
// 剪枝四:如果该元素与左边元素相等,说明该搜索分支重复,直接跳过
if (i > start && choices[i] === choices[i - 1]) {
continue;
}
// 尝试:做出选择,更新 target, start
state.push(choices[i]);
// 进行下一轮选择
backtrack(state, target - choices[i], choices, i + 1, res);
// 回退:撤销选择,恢复到之前的状态
state.pop();
}
}
[class]{}-[func]{subsetSumII}
/* 求解子集和 II */
function subsetSumII(nums: number[], target: number): number[][] {
const state = []; // 状态(子集)
nums.sort(); // 对 nums 进行排序
const start = 0; // 遍历起始点
const res = []; // 结果列表(子集列表)
backtrack(state, target, nums, start, res);
return res;
}
```
=== "C"
@@ -939,9 +1141,9 @@ comments: true
if (target == 0) {
vector *tmpVector = newVector();
for (int i = 0; i < state->size; i++) {
vectorPushback(tmpVector, state->data[i]);
vectorPushback(tmpVector, state->data[i], sizeof(int));
}
vectorPushback(res, tmpVector);
vectorPushback(res, tmpVector, sizeof(vector));
return;
}
// 遍历所有选择
@@ -958,7 +1160,7 @@ comments: true
continue;
}
// 尝试:做出选择,更新 target, start
vectorPushback(state, choices->data[i]);
vectorPushback(state, choices->data[i], sizeof(int));
// 进行下一轮选择
backtrack(state, target - *(int *)(choices->data[i]), choices, i + 1, res);
// 回退:撤销选择,恢复到之前的状态
@@ -969,7 +1171,7 @@ comments: true
/* 求解子集和 II */
vector *subsetSumII(vector *nums, int target) {
vector *state = newVector(); // 状态(子集)
qsort(nums->data[0], nums->size, sizeof(int), comp); // 对 nums 进行排序
qsort(nums->data, nums->size, sizeof(int *), comp); // 对 nums 进行排序
int start = 0; // 子集和
vector *res = newVector(); // 结果列表(子集列表)
backtrack(state, target, nums, start, res);