https://leetcode.com/problems/merge-sorted-array/ In this leetcode question, this is the logic, I used

class Solution {
public:
void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
    int i = 0;
    int j = 0;
    int k = 0;
    vector<int> ans;
    
    while (i<m && j<n) {
        
        if (nums1[i] < nums2[j]){
            ans[k  ] = nums1[i  ];
            
        }
        else {
            ans[k  ] = nums2[j  ];
            
        }
    }           
    while (i<m) {
        ans[k  ] = nums1[i  ];
        
    }            
    while (j<n) {
        ans[k  ] = nums2[j  ];
    }        
    for (int h = 0; h<(m n); h  ) {
        nums1[h] = ans[h];
    }
    }
    };

while running the code, I get this runtime error. Error Image How do I solve this

CodePudding user response：

This is a vector of size zero

vector<int> ans;

This code attempts to change an element of the size zero vector.

ans[k  ] = nums1[i  ];

That's the cause of your error.

If you want to add an element to the end of a vector use push_back

ans.push_back(nums1[i  ]);

C vectors don't change size automatically, you have to use push_back or resize or insert or something similar.

Alternatively make the vector the correct size to begin with

vector<int> ans(m   n);

though I prefer the push_back method myself.