1. 题目链接

118. 杨辉三角

2. 题目代码

正确代码

class Solution {
public:
    vector<vector<int>> generate(int numRows) {
        vector<vector<int>> result(numRows);
        for(int i = 0; i < numRows; ++i){
            result[i].resize(i + 1);
            result[i][0] = 1;
            result[i][i] = 1;
            for(int j = 1; j < i; ++j){
                result[i][j] = result[i - 1][j - 1] + result[i - 1][j];
            }
        }
        return result;
    }
};

错误代码

原因：没有初始化矩阵就进行访问

class Solution {
public:
    vector<vector<int>> generate(int numRows) {
        //vector<vector<int>> result(numRows);
        vector<vector<int>> result;

        for(int i = 0; i < numRows; ++i){
            //result[i].resize(i + 1);
            result[i][0] = 1;
            result[i][i] = 1;
            for(int j = 1; j < i; ++j){
                result[i][j] = result[i - 1][j - 1] + result[i - 1][j];
            }
        }
        return result;
    }
};