PPT Slide

// Given sorted b, return the integer k that satisfies

// b[0..k] <= x < b[k+1..b.length-1]

public static int binarySearch( int [ ] b) {

int k= -1;

int j= b.length;

// Invariant: -1 <= k < j <= b.length and

// b[0..k] <= x < b[k+1..b.length]

while (k+1 != j) {

int e = (k+j)/2;

// We know -1 <= k < e < j <= b.length

if ( b[e] <= x ) k= e;

else j= e;

}

return k;

}