feat(src): add 55-canJump, 56-merge

Author: kwu130

src/55-canJump.cpp

@@ -0,0 +1,33 @@
+//
+// Created by 1412 on 2025/11/3.
+//
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Solution {
+public:
+    bool canJump(vector<int>& nums) {
+        int reach = 0;
+        for (int i = 0; i < nums.size() && i <= reach; ++i) {
+            reach = max(reach, i + nums[i]);
+            if (reach >= nums.size() - 1) return true;
+        }
+        return false;
+    }
+};
+
+void test() {
+    Solution s;
+    vector<int> nums = {2, 3, 1, 1, 4};
+    assert(s.canJump(nums) == true);
+
+    nums = {3, 2, 1, 0, 4};
+    assert(s.canJump(nums) == false);
+}
+
+int main() {
+    test();
+    return 0;
+}

src/56-merge.cpp

@@ -0,0 +1,65 @@
+//
+// Created by 1412 on 2025/11/3.
+//
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Solution {
+public:
+    vector<vector<int>> merge(vector<vector<int>>& intervals) {
+        ranges::sort(intervals);
+        vector<vector<int>> res;
+        for (const auto& interval : intervals) {
+            if (res.empty() || res.back()[1] < interval[0]) {
+                res.emplace_back(interval);
+            } else {
+                res.back()[1] = max(res.back()[1], interval[1]);
+            }
+        }
+        return res;
+    }
+};
+
+void test() {
+    Solution s;
+    vector<vector<int>> intervals = {
+        { 1,  3},
+        { 2,  6},
+        { 8, 10},
+        {15, 18}
+    };
+    vector<vector<int>> expect = {
+        { 1,  6},
+        { 8, 10},
+        {15, 18}
+    };
+    vector<vector<int>> res = s.merge(intervals);
+    assert(res == expect);
+
+    intervals = {
+        {1, 4},
+        {4, 5}
+    };
+    expect = {
+        {1, 5}
+    };
+    res = s.merge(intervals);
+    assert(res == expect);
+
+    intervals = {
+        {4, 7},
+        {1, 4}
+    };
+    expect = {
+        {1, 7}
+    };
+    res = s.merge(intervals);
+    assert(res == expect);
+}
+
+int main() {
+    test();
+    return 0;
+}