添加C++、计算机网络、音视频、Leetcode118、119、122

Problems/LeetcodeProblems/118-pascals-triangle.h

@@ -0,0 +1,21 @@
+class Solution {
+public:
+    vector<vector<int>> generate(int numRows) {
+        vector<vector<int>> triangle;
+        for(int i = 0; i < numRows; i++){
+            vector<int> v;
+            if(i==0){
+                v.push_back(1);
+            }
+            else{
+                v.push_back(1);
+                for(int j = 0; j < triangle[i-1].size()-1; j++){
+                    v.push_back(triangle[i-1][j] + triangle[i-1][j+1]);
+                }
+                v.push_back(1);
+            }
+            triangle.push_back(v);
+        }
+        return triangle;
+    }
+};

Problems/LeetcodeProblems/119-pascals-triangle-ii.h

@@ -0,0 +1,13 @@
+class Solution {
+public:
+    vector<int> getRow(int rowIndex) {
+        vector<int> v(rowIndex + 1, 0);
+        v[0] = 1;
+        for (int i = 0; i < rowIndex; i++){
+            for(int j = i + 1; j > 0; j--){
+                v[j] += v[j - 1];
+            } 
+        }
+        return v;
+    }
+};

Problems/LeetcodeProblems/122-best-time-to-buy-and-sell-stock-ii.h

@@ -0,0 +1,26 @@
+class Solution {
+public:
+    int maxProfit(vector<int>& prices) {
+        int max=0, begin=0, end=0;
+        bool up=false, down=false;
+        for (int i=1; i<prices.size(); i++) {
+            if (prices[i] > prices[i-1] && up==false){ // goes up
+                begin = i-1;
+                up = true;
+                down = false;
+            }
+            if (prices[i] < prices[i-1] && down==false) { // goes down
+                end = i-1;
+                down = true;
+                up = false;
+                max += (prices[end] - prices[begin]);
+            }
+        }
+        // edge case 
+        if (begin < prices.size() && up==true){
+            end = prices.size() - 1;
+            max += (prices[end] - prices[begin]);
+        }
+        return max;
+    }
+};