public int nthUglyNumber(int n) {

int[] f = new int[n];

f[0] = 1;

int t2 = 0, t3 = 0, t5 = 0;

for (int i = 1; i < n; i++) {

f[i] = Math.min(Math.min(f[t2] * 2, f[t3] * 3), f[t5] * 5);

if(f[i] >= f[t2] * 2) {

t2++;

}

if(f[i] >= f[t3] * 3) {

t3++;

}

if(f[i] >= f[t5] * 5) {

t5++;

}

}

return f[n - 1];

}