Poj 1502 MPI maelstrom Dijkstra

The minimum time required to send information from the first vertex to all other vertices. Input in the form of the following triangle. If it cannot be passed from I to J, it is represented by X.
Question: Pay attention to the input.

#include <iomanip>#include <iostream>using namespace std;#define INF 200000000int map[101][101], n;int mark[101], dist[101];int Dijkstra (){int i, j, k, min, max;memset(mark,0,sizeof(mark));for ( i = 1; i <= n; i++ )dist[i] = map[1][i];dist[1] = 0;mark[1] = 1;for ( i = 1; i <= n; i++ ){min = INF;for ( j = 1; j <= n; j++ )if ( !mark[j] && dist[j] < min ){k = j;min = dist[j];}if ( min == INF ) break;mark[k] = 1;dist[k] = min;for ( j = 1; j <= n; j++ )if ( !mark[j] && dist[k] + map[k][j] < dist[j] )dist[j] = dist[k] + map[k][j];}max = 0;for ( i = 1; i <= n; i++ )if ( dist[i] > max )max = dist[i];return max;}int main(){cin >> n;int i, j, num;for ( i = 2; i <= n; i++ ){for ( j = 1; j < i; j++ ){cin >> num;if ( cin.fail () ){map[i][j] = map[j][i] = INF;cin.clear ();cin.get ();}elsemap[i][j] = map[j][i] = num;}}cout << Dijkstra () << endl;return 0;}