下面Floyd算法中，横线处应该填入的是（ ）。
#include <iostream>
using namespace std;
#define N 21
#define INF 99999999
int map[N][N];
int main() {
int n, m, t1, t2, t3;
cin >> n >> m;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
if (i == j)
map[i][j] = 0;
else
map[i][j] = INF;
}
}
for (int i = 1; i <= m; i++) {
cin >> t1 >> t2 >> t3;
map[t1][t2] = t3;
}
for (int k = 1; k <= n; k++)
for (int i = 1; i <= n; i++)
for (int j = 1; j <= n; j++)
if (__________) // 在此处填入选项
map[i][j] = map[i][k] + map[k][j];
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
cout.width(4);
cout << map[i][j];
}
cout << endl;
}
}
map[i][j] < map[i][k] + map[k][j]
map[i][j] > map[i][k] + map[k][j]
map[i][j] > map[i][k] - map[k][j]
map[i][j] < map[i][k] - map[k][j]