How to write the MATLAB code for generating such figure?

Below is the MATLAB code for generating the figure as described. The code generates random y-values to simulate total cost, then finds the minimum cost up to the current point for each run number, and plots both the solutions and the best solution up to that point.

x = 1:100; % Run numbers 
y = rand(size(x)) * 300 + 9200; % Simulate random total costs 
y2 = y; % Initialize best solution array 
% Loop through to find the best solution up to the current run 
for i = 2:size(x,2) 
    y2(i) = min(y2(i-1),y(i)); 
end 
% Scatter plot for solutions 
scatter(x,y,'x'); 
xlabel('Run number'); % Label for x-axis 
ylabel('Total cost'); % Label for y-axis 
hold on % Hold on to add another plot to the figure 
% Line plot for the best solution 
plot(x,y2); 
hold off % Release the hold to finish plotting 
% Add legend 
legend('Solutions','Best solution'); 
% Set y-axis limits 
ylim([9100 9700]); 

When you run this code in MATLAB, it will generate a scatter plot of the solutions and a line plot that tracks the best solution found up to each run number. The y-axis is limited to the range [9100, 9700] as specified.

For more information about ‘legend’ function refer the document below:

https://www.mathworks.com/help/matlab/creating_plots/add-legend-to-graph.html